Method and Apparatus for Composite User Interface Generation

ABSTRACT

A method for directing messages between a composite user interface and at least one source application. A message is to be directed to a predetermined set of services, each service executes a command specified by the message and the message comprises details of the predetermined set of services. Each service in the predetermined set of services uses said details to determine whether the message should be sent to another service, and if it is determined that the message should be sent to another service transmits the message to an appropriate service.

FIELD OF INVENTION

The present invention relates to methods and systems for generatingcomposite user interfaces, and to methods and systems for directingmessages between a composite user interface and a plurality of sourceapplications.

BACKGROUND OF INVENTION

Computer users routinely need to use a plurality of differentapplications in order to complete tasks allocated to them, and eachapplication typically has a separate user interface. Switching betweenthe different user interfaces of the different applications in order tocomplete a given task considerably degrades user efficiency. It willoften be the case that different applications are supplied by differentvendors and accordingly their user interfaces have a different “look andfeel”, further degrading operator efficiency.

For example, in order to process customer enquiries, operators in a callcentre may need to access a customer management application to accesscustomer details, a billing application to access customer accountinformation, and a payment application to process any payment which maybe made by the customer over the telephone, for example by credit card.Working in this manner is inefficient, given that the operator isrequired to switch between applications in order to complete some tasks.Furthermore, a customer will typically remain on the telephone while theoperator uses these different applications, and it is thereforeadvantageous to speed up the processing of enquires, in order to offer ahigher quality customer service.

Various proposals have been made to enhance user efficiency whenmultiple applications need to be used.

The multiple applications can be combined into a single product orproduct suite. While such a proposal provides great increases in userefficiency, it is difficult and expensive to implement. Furthermore,such a combined product or product suite will typically have a differentuser interface from those used previously, therefore meaning that usersneed to be trained in use of the combined product, further increasingcost.

It has alternatively been proposed that the multiple application can becombined in some way. For example, all requests can be passed to asingle one of the applications, and this application can be adapted toforward requests to an appropriate source application. Such a solutiontypically requires considerable customisation if it is to work in underall circumstances that may routinely arise, making such a solutiondifficult to implement.

It is an object of the present invention to obviate or mitigate at leastsome of the problems outlined above.

SUMMARY OF INVENTION

In accordance with one aspect, the present invention provides a methodand system for processing messages within a computer system. A messagecomprising details of a predetermined set of services and a command isreceived, and the command is executed. The message is then transmittedto a service in said predetermined set of services. In accordance withsome embodiments of the invention, a plurality of services is providedand each service executes a respective command specified by the message.Each service in the predetermined set of services uses said details todetermine whether the message should be sent to another service. If itis determined that the message should be sent to another service themessage is then transmitted to an appropriate service.

The present invention thus provides a distributed messaging method, inwhich message routing is determined by data contained within individualmessages, and is achieved by the services to which they are directed.The invention therefore removes the need for any central messagingservice which is responsible for all message routing operations. Inorder to allow distributed routing, the message may comprise an orderedlist of pairs, a first element of each pair representing a service inthe predetermined set of services, and a second element of each pairrepresenting a command to be executed by that service, thus each servicecan determine a command to be executed and can determine a next serviceto which the message should be directed.

The term service is to be understood broadly to cover any processingmeans or processing module which is adapted to receive a message, carryout processing specified by that message, and forward the message to afurther service using data specified within the message. The servicescan be implemented using computer program code means. For example eachservice can be implemented as an instance of a class defined in anobject oriented programming language such as Java or C++. Each classrepresenting a service preferably has an associated service handlerclass which specifies a method configured to execute a command directedto an instance of the respective service class. Advantageously, eachservice object references a plurality of service handler objects whichare instances of the respective service handler class. By providing aplurality of service handler objects in this way, a single service maycarry out a plurality of commands concurrently, thereby improvingprocessing efficiency.

In one embodiment, a plurality of services in the predetermined set ofservices may operate within a single operating system process, whilst inother embodiments of the invention some services in the predeterminedset of services may operate within a plurality of operating systemprocesses. Providing a plurality of processes enhances scalability,while operating a plurality of services within a single operating systemprocess can result in improved performance. It is preferred that anattempt is made to locate a service within the current operating systemprocess, and if such an attempt is successful, relatively costly interprocess communication can be avoided. However, if the attempt isunsuccessful, the message may be transmitted to a messaging servicewithin the current operating system process which is responsible forinter-process communication, and the messaging service may transmit themessage to a different operating system process, thus providingscalability. For example, in some embodiments, the system and method ofthe invention allow different services provided on different computersconnected to a computer network to be handled in a similar manner todifferent services provided within different operating system processeson a single computer. It is preferred that messaging is achieved usingthe Java Messaging Service (JMS).

In some embodiments, a message may be directed between a composite userinterface and at least one source application, such that the compositeuser interface can be used to interface with the at least one sourceapplication. A message emanating from a composite user interface may bedirected to a service which generates at least one further message. Thefurther message may comprise details of a further set of services towhich the further message is to be directed, and the further message canthen be directed in the distributed manner described above. The at leastone further message may be processed by one of services in said furtherset of services to produce a request which is transmitted to the atleast one source application. Messaging methods provided by embodimentsof the present invention offer particular benefits in composite userinterface applications given that communication between a compositeapplication and one or more source applications can be provided in adecoupled manner. Thus, the invention allows composite user interfacesto be conveniently and efficiently provided allowing users to use acomposite user interface to control a plurality of source applications,offering considerable benefits in user productivity.

Data from the source application may be used to create a responsemessage in response to said request. The response message can again behandled in the distributed manner described above. An aggregationservice in the set of response services may receive a plurality ofresponse messages and may combine said plurality of response messages tocreate a further response message. Thus, the aggregation service caneffectively combine a plurality of messages containing user interfaceelements to create a composite user interface.

In some embodiments, the aggregation service may also generateadditional user interface elements which are combined with said userinterface to generate said composite user interface. Adding additionaluser interface elements in this way can be useful in providing a unified“look and feel” throughout a composite application.

The aggregation service may combine said user interface elements togenerate the composite user interface in accordance with predefinedconfiguration data, which can suitably be stored in a hierarchical datastructure. A first entity within the hierarchical data structure mayrepresent the composite user interface, and child entities of said firstentity may represent the plurality of source user interface elements forinclusion in the composite interface. Each child entity of the firstentity can in turn have child entities and so on. Using a hierarchicaldata structure is advantageous as it allows easy scalability where userinterface elements are nested within other user interface elements.

In some embodiments, each child entity has an associated parameterindicating whether the respective source user interface element ismandatory. The aggregation service may receive a user interface element,store data indicative of receipt of said user interface element in adata structure associated with said hierarchical data structure, andwhen all source user interface elements having an associated parameterindicating that the source user interface element is mandatory have beenreceived, combine said plurality of source data items to generate saidcomposite user interface. Differentiating between mandatory andnon-mandatory user interface elements in this way can provideconsiderable benefits in terms of efficiency, and allows a userinterface to be provided as soon as key components have been received.

The composite user interface may be generated in an internal format,which may be converted to an output format using output configurationdata. This allows the invention to be easily adapted for use with aplurality of different output formats, assuming only that appropriateconfiguration data is provided.

A transformation service may receive data from the at least one sourceapplication and transform said data into an internal format, saidtransformed data being contained in said plurality of response messages.Said transformation may be effected in a plurality of different ways,for example using regular expressions, or using a class defined in anobject oriented programming language to transform data.

In some embodiments, the aggregation service may be configured to expectto receive a predetermined number of response messages in response totransmission of said further message, and said further response messagemay be generated when the predetermined number of response messages hasbeen received.

According to a further aspect of the present invention, there isprovided a method and system for generating a composite user interfacefor presentation to a user. The method comprises generating requests fora plurality data items for inclusion in the interface, transmitting eachrequest to one of a plurality of source applications, and combining dataitems received in response to at least one of said requests to generatethe user interface. At least some of the predetermined plurality of dataitems are mandatory, and at least some of the predetermined plurality ofdata items are optional, and the composite user interface is generatedwhen all mandatory data items have been received. This aspect of thepresent invention allows composite user interfaces to be generated morequickly, given that it is necessary to await receipt only of mandatoryuser interface elements.

The method preferably comprises generating said plurality of requestsfrom a single request such as a HTTP request entered by a user using aweb browser. The plurality of requests are decoupled from the singlerequest. Said single request may be received by an aggregation servicefunctioning in a manner similar to that described above.

A further aspect of the present invention, provides a method forgenerating a composite user interface for presentation to a user, saidcomposite user interface comprising a plurality of user interfaceelements generated from source interface elements provided by at leastone source application. The method comprises generating a plurality ofrequest messages, transmitting each request message to an appropriatesource application and receiving a plurality of source interfaceelements from the at least one source application. Source interfaceelements are compared with a plurality of predefined source interfacetemplates; and if said received source interface element matches apredefined source interface template, at least one user interfaceelement is extracted for inclusion in said composite user interface. Atleast one of said source interface elements may be a HTML document, or apart of a HTML document such as, for example, a text box, fixed textdata, or buttons responsive to selection by a pointing device.

The method may further comprise: creating an internal representation ofeach extracted user interface element, forwarding said internalrepresentations to an aggregation service, and combining said internalrepresentations to create an internal representation of the compositeuser interface. The method may further comprise transforming saidinternal representation of the composite user interface into an outputformat specified by predefined configuration data. By using internalrepresentations in this way, the process of composite user interfacecreation can be carried out independently of any required outputformats, meaning that the method can be easily applied to a wide varietyof different output formats (e.g. HTML for a web based output), assumingonly that necessary configuration data is supplied.

The invention also provides a carrier medium such as a disk or CD-ROMcarrying computer readable program code means for controlling a computerto carry out any of the methods described above.

The invention also provides a computer apparatus comprising a programmemory containing processor readable instructions, and a processor forreading and executing the instructions contained in the program memory.The processor readable instructions comprising instructions controllingthe processor to carry out any of the methods described above.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the present invention will now be described, by way ofexample, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic overview of a system for composite applicationcreation in accordance with an embodiment of the present invention;

FIG. 2 is a schematic illustration showing the system of FIG. 1 infurther detail;

FIG. 3 is a schematic illustration of process management within theserver of FIG. 2;

FIG. 4 is a schematic overview of Java classes used to implement someparts of the architecture of FIG. 3;

FIGS. 4A to 4V are UML class diagrams showing the classes of FIG. 4 infurther detail;

FIG. 5 is a schematic overview of Java classes used to implement thenodes illustrated in FIG. 3;

FIGS. 5A to 5J are UML class diagrams showing the classes of FIG. 5 infurther detail;

FIG. 6 is a state transition diagram showing transitions between classesof FIG. 5 used to represent state information related to nodes;

FIG. 7 is a schematic overview of Java classes used to implement theservices illustrated in FIG. 3;

FIGS. 7A to 7F are UML class diagrams showing the classes of FIG. 7 infurther detail;

FIG. 8 is a schematic overview of Java classes class used to implementmessaging within the architecture of FIG. 3;

FIGS. 8A to 8K are UML class diagrams showing the classes of FIG. 8 infurther detail;

FIG. 9 is a schematic illustration showing creation of a process withinthe architecture of FIG. 3;

FIG. 10 is a schematic illustration showing creation of a node withinone of the processes of FIG. 3;

FIG. 11A is a schematic overview of a messaging process in accordancewith an embodiment of the present invention;

FIG. 11B is a flowchart showing the messaging process of FIG. 11A infurther detail;

FIGS. 12A to 12D are schematic illustrations showing the messaging ofFIGS. 11A and 11B in further detail;

FIG. 13 is a schematic illustration showing distributed messaging asillustrated in FIGS. 12A to 12D;

FIG. 14 is a schematic illustration of the logical architecture of theweb server and the server of FIG. 2;

FIG. 15 is a schematic illustration showing how parts of thearchitecture of FIG. 14 cooperate to provide composite user interfaces;

FIG. 16 is a table showing invocation parameters used by the web serverof FIG. 2;

FIG. 17 is a table showing invocation parameters used by the server ofFIG. 2;

FIG. 18 is a table showing Hypertext Markup Language (HTML) tags whichmay be used in embodiments of the present invention;

FIG. 19 is an extract from a configuration file, illustrating howvarious parameters can be initalised;

FIG. 20 is a tree diagram illustrating configuration data for the serverand web server of FIG. 2;

FIG. 21 is a tree diagram showing configuration data pertinent to theCommunications Layer (CL) services of FIG. 14;

FIGS. 22 and 23 are tree diagrams showing configuration data pertinentto the Data Transformation (DT) services of FIG. 14;

FIGS. 24, 25 and 26 are tree diagrams showing configuration datapertinent to the User Experience Manager (UXM) service of FIG. 14;

FIG. 27 is a tree diagram showing configuration data pertinent to theApplication Lockdown Framework (ALF) illustrated in FIG. 14;

FIG. 28 is a tree diagram showing configuration data for the web serverillustrated in FIG. 14;

FIG. 29 shows configuration data for the IDM illustrated in FIG. 14;

FIG. 30 is a schematic illustration showing a relationship between a UXMtree and a UXMObject tree;

FIG. 31 is a schematic illustration showing how a HTML document may beconverted into a plurality of UXM objects;

FIG. 32 is a schematic illustration of operation of the DT service for aparticular source application; and

FIG. 33 is a HTML code fragment which can be used to generate anIncomingUserRequest message.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 illustrates a system for creating composite applications inaccordance with an embodiment of the present invention. A first sourceapplication provides a first user interface 1, a second sourceapplication provides a second user interface 2, and a third sourceapplication provides a third user interface 3. A composition system 4composes the first, second and third user interfaces to form a firstcomposite user interface 5 and a second composite user interface 6. Itcan be seen that the first composite user interface 5 is created fromthe composition of the first, second and third user interfaces 1, 2, 3,while the second composite user interface 6 is created from thecomposition of the second and third user interfaces 2, 3.

The composition system 4 processes requests from users of the compositeuser interfaces 5, 6 and generates requests to the appropriate sourceapplications. The composition system 4 additionally receives informationfrom the first, second and third applications in response to suchrequests, and uses this information to generate the composite userinterfaces 5, 6.

For example, the composite user interfaces 5 may comprise a number ofpages each containing elements from one or more of the first, second andthird user interfaces 1, 2, 3. That is a first page of the userinterface may be made up solely from the first user interface 1, and asecond page may be up from the combination of part of the second userinterface 2 and part of the third user interface 3, and a third page maycomprise part of the second user interface 2, rearranged by the composerto provided a “look and feel” which is similar to that of the first andsecond pages.

FIG. 2 illustrates the system of FIG. 1 in further detail. The compositeuser interface 5 is displayed to a user by means of a display device 7connected to a PC 8. Similarly, the composite user interface 6 isdisplayed to a user by means of a display device 9 connected to a PC 10.The PCs 8, 10 have means for connection to the Internet 11. The PCs 8,10 can be connected to the Internet 11 via a local area networkconnection, or alternatively via a modem (not shown).

A Web server 12 is also connected to the Internet 11, and stores aplurality of webpages in HTML (Hypertext Markup Language) format whichcan be accessed by the PCs 8, 10. The Web server is connected to aserver 13. This connection can either be a direct connection 14 (asshown in FIG. 2), or alternatively a connection across a network such asthe Internet. The server 13 is in turn connected to three servers 15,16, 17 which respectively execute the first second and thirdapplications to provide the first second and third user interfaces 1, 23. The server 13 is also connected to a database 18 which storesconfiguration data.

In operation, the web server 12 provides HTML documents which form thecomposite user interfaces 5, 6. The composite user interfaces 5, 6 arecreated by processes running on the server 13, which create thecomposite user interfaces from information provided by the servers 15,16, 17, in accordance with configuration data stored in the database 18as described below. Data input by users of the composite interfaces 5, 6is received by the web server 12 and forwarded to the server 13 via theconnection 14. The server 13 processes such data in a predefined manner,and forwards data to the servers 15, 16, 17 as appropriate.

It will be appreciated that in some embodiments of the presentinvention, instead of connection over the Internet 11, the appropriateconnections can be realised through an organisation's Intranet.

Operation of the Web server 12 and the server 13 in creating andmodifying the composite user interfaces 5, 6 is described below.

The server 13 operates using a flexible process framework. FIG. 3illustrates components used within this flexible process framework.

A HostMasterWatchdog component 19 checks if a HostMaster process 20 isalready running, and if not causes a HostMaster process to be started.The HostMaster process 20 is responsible for creating and removingprocesses. The HostMaster process 20 ensures that all created processesare up and running and also passes relevant configuration information tosuch processes. Any host operating in accordance with the processframework described herein runs a single instance of theHostMasterWatchdog component 19 and the HostMaster process 20.

In the illustration of FIG. 3, a server runs a first process 21 and asecond process 22. The first process comprises two nodes 23, 24 and thesecond process comprises two nodes 25, 26. Nodes are containers for userservices, and are described in further detail below. Each of theprocesses 21, 22 includes a respective process agent 27, 28 which isresponsible for starting nodes within the respective process, andrestarting nodes within the process in case of failure. Operation ofnodes within the processes 22, 23 is managed by respective node managercomponents 29, 30.

In preferred embodiments of the present invention all entities in theframework illustrated in FIG. 3 except the HostMasterWatchdog 19 areimplemented as instances of Java™ classes, thereby providing and objectoriented implementation. Details of such an implementation are describedbelow. In the following description, programming language constructssuch as classes, objects, interfaces and methods, are given their usualmeaning within the Java programming language.

The HostMasterWatchdog process 19 regularly checks the state of theHostMaster process 20. If the HostMasterWatchdog process 19 finds aHostMaster process 20 in an invalid state, or fails to find a HostMasterprocess, it attempts to shutdown any existing HostMaster process 19 andstarts a new HostMaster process. If this is initially unsuccessful,repeated retries are attempted until a user manually exits theHostMasterWatchdog 19. The HostMasterWatchdog process 19 is typicallywritten in a conventional high level programming language such as C, anda HostMasterWatchdog implementation will therefore need to be writtenfor each different platform on which the framework is to operate.However, in preferred embodiments of the invention, the other componentsare all implemented as instances of Java classes, providing portabilitybetween platforms.

FIG. 4 illustrates the classes used to implement other entitiesillustrated in FIG. 3. Individual classes are illustrated in furtherdetail in FIGS. 4A to 4V.

In addition to the entities illustrated in FIG. 3, each of the processes21, 22 maintains a component registry by creating and maintaining aninstance of a DefaultComponentRegistry class 31 (FIG. 4A), whichimplements a ComponentRegistry interface 32 (FIG. 4B). This registryallows objects to be added to the registry using a registerObject(ObjectC) method specified in the ComponentRegistry interface 32. Objects addedto the registry can be monitored and administered using methods providedby the DefaultComponentRegistry class 31, and therefore such componentscan receive notifications of state changes in other components in theregistry.

Each of the entities illustrated in FIG. 3 is represented by acorresponding class shown in FIG. 4. The HostMaster process isrepresented by an instance of a HostMaster class 33 (FIG. 4C). TheProcessAgent process is represented by an instance of a ProcessAgentclass 34 (FIG. 4D), which in turn references an instance of aNodeManager class 35 (FIG. 4E) by means of a private variablemNodeManager within the ProcessAgent class 34. The NodeManager class 35contains details of individual nodes. Classes used to represent suchnodes will be described in further detail below.

Appropriate instances of the HostMaster 33 and ProcessAgent 34 classesset out above are registered with an instance of theDefaultComponentRegistry class 31. It can be seen that both HostMasterclass 33 and ProcessAgent class 34 implement a ComponentAware interface36 (FIG. 4F). This specifies a single method getComponentClass( ) whichall implementing classes must provide. Each class defines this method soas to locate an appropriate corresponding component class. In the caseof the HostMaster class 33, a HostMasterComponent class 37 (FIG. 4G) islocated by the getComponentClass( ) method. In the case of theProcessAgent class 34, the getComponentClasss( ) method locates theProcessAgentComponent class 38 (FIG. 4H).

The component classes provide a convenient manner for encapsulatingadministrative information separately from functionality. When an objectimplementing the ComponentAware interface 36 is registered with theinstance of the DefaultComponentRegistry class 31, the getCompoentClass() method is used to locate the appropriate component class, and thiscomponent class is then instantiated and registered with the instance ofDefaultComponentRegistry. These component classes in turn links with therespective object which is being registered.

It should be noted that all entities to be registered with theDefaultCompoentRegistry will not necessarily implement theComponentAware interface 36. If the DefaultCornponentRegistry objectdetermines that an object being registered does not implement thisinterface, an instance of a GenericComponent class 39 (FIG. 4I) is usedto register the object with the DefaultComponetRegistry object. Thisclass simply allows the object being registered to be located, butprovides no administrative functions.

FIG. 4 illustrates the hierarchy of classes used to representcomponents. The highest level of the hierarchy comprises a Componentinterface 40 (FIG. 4J) which is implemented by a ComponentBase class 41(FIG. 4K). The ComponentBase class 41 has two subclasses, a G2Componentclass 42 (FIG. 4L) and a AdminComponent class 43 (FIG. 4M). TheAdminComponent class 43 acts as a superclass for three classes which areused to implement administrative functions. A CascadingAgentComponentclass 44 (FIG. 4N) is used for communication between an instance of theHostMaster class 33 and an instance of the ProcessAgent class 34. AnHTMLAdaptorComponent class 45 (FIG. 4O) is used by theHostMasterComponent 37. An RMIConnectorServerComponent 46 (FIG. 4P) isused by the ProcessAgentComponent 38 for communication via Remote MethodInvocation (RMI) as provided by the Java programming language. TheG2Component class 42 acts as a superclass for components describedabove. Specifically, the GenericComponent class 39, theProcessAgentComponent class 38 and the HostMasterComponent class 37 areall subclasses of the G2Component class 42. Additionally, theG2Component class 42 is a superclass for a ServiceComponent class 47(FIG. 4Q), and a NodeComponent class 48 (FIG. 4R).

It has been mentioned above that an instance of the NodeManager class 35is referenced by a private variable in instances the ProcessAgent class34. Both the ProcessAgent class 34 and the NodeManager class 35 bothimplement a NodeAdmin, interface 49 (FIG. 4S).

A number of other classes are also illustrated in FIG. 4. A G2Runtimeclass 50 (FIG. 4T) is used as a master class for the runtime of allclasses illustrated in FIG. 4.

A ComponentAddress class 51 (FIG. 4U) is used to address the componentsof the architecture of FIG. 3. An exception AdminException 52 is usedfor exeptions thrown by subclasses of the AdminComponent class 43.

An MBeanConfig class 53 (FIG. 4V) is used to represent configurationinformation of an MBean™. The components implemented as subclasses ofthe ComponentBase class 41 all inherit a private variable of type Objectwhich represents an MBean used to implement that component. TheMbeanConfig class 53 represents the configuration of such MBean objects.

As described above, the HostMaster process 20 (FIG. 3) is represented bya HostMaster object, and registered using a HostMasterComponent object.The HostMasterComponent allows the HostMaster to be notified ofProcessAgent creation and removal. This is described in further detailbelow.

The ProcessAgent processes 27, 28 (FIG. 3) are represented by respectiveProcessAgent objects which allow administration of nodes within thatprocess, via appropriate NodeManager object(s).

As shown in FIG. 3, processes contain nodes, which are managed by aNodeManager object. Nodes in turn comprise one or more services. A nodeis responsible for its contained services, and does not directly deliverany user functionality. Each node is represented by a suitable object,and FIG. 5 shows an overview of appropriate classes. The individualclasses are shown in Further detail in FIGS. 5A to 5J.

The NodeManager class 35 instantiates and uses an instance of aNodeFactory class 54 (FIG. 5A) which creates instances of a MasterNodeclass 55 (FIG. 5B), and these instances are used to represent the nodes23, 24, 25, 26 (FIG. 3). It should be noted that the MasterNode class 55implements a Node interface 56 (FIG. 5C) which specifies methodsrequired to implement basic functionality. The NodeManager classinstantiates instances of a NodeNotFoundException 35 a, when it isrequested to act upon a MasterNode object of which it is not aware.

Each MasterNode object has associated with it one or more router threadswhich are used to route messages within the node. These threads arerepresented by a private variable mRouterThreadPool in the MasterNodeclass 55, which is an instance of a class (not shown) implementing aPool interface 57 (FIG. 5D). The class implementing the Pool interfacecontains objects represented by instances of a RouterThread class 58(FIG. 5E), which represent the router threads.

Each node has associated with it a cache represented by an instance of aReplicatedCache class 59 (FIG. 5F) which is a subclass of aTimeStampedCache class 60 (FIG. 5G), which in turn implements a Cacheinterface 61 (FIG. 5H). The purpose of the ReplicatedCache object is tostore state information related to each service contained in that node,and this information can be used to restart services in the event of asystem crash. Furthermore, the cache is replicated between multiplenodes, such that if one node crashes, the node and its associatedservices can be restarted using cache data from the node containing thecopy of the cache data. The ReplicatedCache class 59 provides methods toensure synchronisation of data in the copy cache.

Each node also comprises an addressable registry, represented by aninstance of the ComponentRegistry class 62 (FIG. 5I) This class allowsservices within a node to be registered with the node, and also provideslook up functions which can be used to locate services present withinthe node.

A node represented by a MasterNode object can have one of eight possiblestates, each of which is represented by a corresponding class. Theprivate variable mState indicates an object indicating this stateinformation. Each of the eight classes which may be stored in the mStatevariable implements the Node interface 56 which specifies methodsrelevant to transitions between states.

The state information is infact represented by instances of classeswhich are subclasses of an AbstractNode class 63 (FIG. 5J) which itselfimplements the node interface 56.

A class CreatedNode 64 represents a node which has been created but notyet initialised. A class InitializedNode 65 is used to represent a nodefollowing initialisation. A class StoppedNode 66 represents aninitialised node which is not currently running. When a node isstarting, its state is represented by a class StartingNode 67. A classRunningNode 68 represents a node which has been started and is running.A node which is about to stop running is represented by a StoppingNodeclass 69. Classes FailedNode 70 and RecoveringNode 71 are used torepresent node failure. Each of these classes specifies a constructormethod taking as its sole parameter the MasterObject to which itbelongs, and the also provides five methods specified in the Nodeinterface 56—init( ), start( ), stop( ), destroy( ), recover( ). Eachclass representing state therefore provides a number of methods to allowstate change. For each state, only a single method will not throw anInvalidStateException when called.

Transitions between the states represented by the objects set out aboveare now described with reference to FIG. 6. Upon construction of aMasterNode object by instantiation of the MasterNode 55 by theNodeFactory 54, the mState variable points to an instance of theCreatedNode class 64.

Calling the init( ) method provided in the CreatedNode class creates aninstance of InitializedNode 65, which is referenced by the MasterNode torepresent state. When initialisation is complete an instance of theStoppedNode class 66 is created by the InitializedNode instanvce.Calling the start( ) method provided by the StoppedNode class 66 causesan instance of the StartingNode class 67 to be created which is thenreferenced by the MasterNode to represent state. The StartingNode classthen creates an instance of the RunningNode class 68. The only methodwhich provided by the RunningNode class 68 which does not throw theInvalidStateException is the stop( ) method. When this is called aninstance of the StoppingNode class 69 is created, and subsequently afurther instance of the StoppedNode class 66 is created to representstate.

If processing causes an uncaught exception to be thrown, an instance ofthe FailedNode class 70 is created. The only method which can then bevailidly used is recover( ) which creates an instance of the classRecoveringNode 71, before creating an instance of the class StoppedNode66.

Referring back to FIG. 5, it can be seen that the MasterNode class 55implements a NodeStateSource interface 72 which allows instances of aNodeStateListener class 73 to be registered as listeners with MasterNodeobjects.

The preceding description has been concerned with the implementation ofNodes. It has been described that nodes contain services, andappropriate services are now described. Services are managed by a node,and receive and process messages which are sent to them. The classhierarchy used to implement services is now described with reference toFIG. 7. Further details of the classes shown in FIG. 7 are shown inFIGS. 7A to 7F.

Each service is implemented as an object which is an instance of aBaseService class 74 (FIG. 7A), or as an instance of a subclass thereof.The BaseService class 74 implements an Addressable interface 75, whichspecifies a single getAddress method. In the case of the BaseServiceclass 74, it can be seen that a service's address is stored as a privatevariable of type ComponentAddress (shown in FIG. 4)

The BaseService class 74 additionally implements a HandlerContextinterface 76 (FIG. 7B) which specifies features which allow servicehandlers represented by instances of the BaseServiceHandler class 77(FIG. 7C) to be provided within a service to provide functionality.Handlers receive messages addressed to a service, and act upon thosemessages. Thus, handlers provide the functionality of a service. Eachservice will have a predetermined handler class which provides handlers,and this class will be a subclass of the BaseServiceHandler class 77.Each service may have a plurality of instances of the handler class,thus allowing a service to process messages from a plurality of usersconcurrently.

It can be seen that the BaseServiceHandler class 77 implements aMessageHandler interface 78 which allows handling of messages in aunified manner by specifying a single handleMessage( ) method. TheBaseServiceHandler class 77 also implements a ResultListener interface79 which specifies a single method deliverResult.

Instances of the BaseService class 74 use instances of aMessageDispatcher class 80 (FIG. 7D) to dispatch messages within andbetween services. Both the BaseService class 74 and theBaseServiceHandler class 77 implement a MessageRouter interface 81,which allows routing of messages between services using a route( )method. This interface is used by the MessageDispatcher class 80.Routing of messages using these classes is described in further detailbelow.

It can be seen that FIG. 7 additionally illustrates a ServiceFactoryclass 82 (FIG. 7E) which is used to create services, and a Service Stateclass 83 (FIG. 7F) which is used to denote the state of an instance ofthe BaseService class 74 or one of its subclasses. FIG. 7 alsoillustrates a DebugHandler class 84, which is a service handler used fordebugging purposes during development.

FIG. 8 illustrates a hierarchy of classes used to implement messageswhich can be passed between services to be handled by appropriateservice handlers. These classes are shown in further detail in FIGS. 8Ato 8K.

Referring to FIG. 8, it can be seen that the hierarchy used to representmessages is headed by a Message interface 85 (FIG. 8A) which isimplemented by an abstract class AbstractMessage 86 (FIG. 8B). AComandSequenceMessage class 87 (FIG. 8C) extends the AbstractMessageclass 86. An instance of the CommandSequenceMessage class 87 representsmessages which are to be transmitted between services. TheCommandSequenceMessage class has four subclasses representing messagesused in preferred embodiments of the present invention. A UserRequestclass 88 (FIG. 8D) is used to represent messages generated by a user. AUserResponse class 89 (FIG. 8E) is used to represent responses tomessages represented by instances of the UserRequest class 88. AnApplicationRequest class 90 (FIG. 8F) is used to represent requests madeusing Application Programmers' Interface (API) calls, and anApplicationResponse class 91 is used to represent response to messagesreqpresented by the ApplicationRequest class 90.

Each of the message types described above inherits core featuresrequired to implement messaging from the CommandSequenceMessage class 87(FIG. 8C). A private mSequence variable within theCommandSequenceMessage class 87 references an instance of aCommandSequence class 92 (FIG. 8H). The CommandSequence class includesan array of pairs which comprise a command, and a target (that is aservice to which that command is targeted). Each command target pair isrepresented by an instance of a CommandTargetPair class 93 (FIG. 8I). Itcan be seen that CommandSequence acts as a superclass for aUserRequestCommandSequence class 94, a UserResponseCommandSequence class95, an ApplicationRequestCommand-Sequence class 96 and anApplicationResponseCommandSequence class 97. Each of these subclasses ofthe CommandSequence class 92 represents a command sequence appropriateto the corresponding subclass of the CommandSequenceMessage class 87.

The state of any message represented by a subclass of theAbstractMessage class 86 is represented by a private mState variablewhich references an instance of a MessageState class 97 (FIG. 8J).

The CommandSequenceMessage class 87 also has as a subclass aSingleCommandMessage class 98 (FIG. 8K) which represents a messagehaving a single command and a single target. The SingleCommandMessageclass in turn has a SystemRequest class 99 a and a ServiceRequest class99 b as subclasses.

Having described the various classes used to implement that which isillustrated in FIG. 3, and having also described the classes used toimplement messaging, the manner in which the components of FIG. 3operate together and the manner in which messaging is achieved is nowdescribed with reference to FIGS. 9 to 13. In the following description,objects are denoted by the reference numerals followed by a prime symbol(′). Where appropriate, reference numerals associated with the class ofwhich an object is an instance are used.

Referring first to FIG. 9, creation of ProcessAgents in the architectureof FIG. 3 is illustrated. As described above a HostMasterWatchDogprocess 19 creates a HostMaster object 33′. The HostMaster object hasassociated with it a G2Runtime object 50′ which can be used to locate aDefaultComponentRegistry object 31′ using a getComponentRegistry( )method. The HostMaster object 33′ is then registered within theDefaultComponentRegistry object 31′ this in turn creates aHostMasterComponent object 37′.

The HostMaster uses configuration data to determine how manyProcessAgent objects it needs to create. For each ProcessAgent objectwhich is to be created, a CascadingAgentComponent 44′ is created, andthis component in turn communicates with a respective ProcessAgentobject 34′ which is created within its own Java Virtual Machine. Themain ( ) method of the ProcessAgent object 34′ is configured to carryout the work of the Process Agent. The ProcessAgent object 34′ has anassociated G2Runtime object 50″ which is used to locate aDefaultComponentRegistry object 31″. This in turn creates aProcessAgentComponent object 38′.

The Component objects created by instances of theDefaultComponentRegistry class as described above allow administrationof both HostMaster and ProcessAgent objects. As described above both theHostMaster object 33′ and the ProcessAgent object 34′ have associatedDefaultComponentRegistry objects 31′ and 31″, and both theseDefaultComponentRegistry objects store details of both theHostMasterComponent object 37′, and the HostMasterComponent object 38′

The CascadingAgentComponent object 44′ and the ProcessAgent object 34′communicate using RMI, and both have RMI clients which are used for thispurpose. As described above, a HostMaster object is responsible formanagement of its associated ProcessAgent objects. This is achieved bycommunication using the component registries described above.Furthermore, a ProcessAgent object may generate “Heart beat” events atpredetermined intervals, and the HostMaster object may listen for suchevents. If such an event is not received at the expected time, or withina predetermined time after the expected time, the HostMaster object thenassumes that the ProcessAgent object has died, and accordingly performsrecovery by instantiating a new ProcessAgent object. Details of thedeath of the earlier ProcessAgent object and creation of the newProcessAgent object are recorded in the appropriate DefaultComponentregistry objects.

FIG. 10 illustrates the process of node creation within a particularprocess. The ProcessAgent object 34′ locates its NodeManager object 35′(referenced by the mNodeManager private variable). It then uses a publiccreateNode method within the NodeManager object 35′ to create a node.The createNode method takes as a parameter a node type, which isrepresented by a NodeType object which is an index and textualdescription of the node to be created. The NodeManager object 35′creates a NodeFactory object 54′ using its constructor which takes noparameters. The createNode method provided by the NodeFactory object 54′is then used to create the desired node. The NodeFactory object 54′creates a MasterNode object 55′ by calling its constructor method whichtakes no parameters.

The MasterNode object 55′ in turn instantiates a CreatedNode object 64′which is referenced by an mState parameter within the MasterNode object55′. An init( ) method provided by the CreatedNode object 64′ is thencalled by MasterNode to initialise the MasterNode object 55′, and thetransitions between states illustrated in FIG. 6 can then occur asnecessary, and the state of the node is set using a setState methodprovided by the MasterNode object 55′. The CreatedNode object 64 in duecourse uses a ServiceFactory object 82′ to create the services requiredby the MasterNode object 64′.

It can be seen from FIG. 4E that the NodeManager class includes aprivate Vector variable mynodes which stores details of all nodesmanaged by a NodeManager object. FIG. 10 schematically illustrates thateach time a MasterNode object is created, it is added to this vectorvariable.

FIGS. 11A and 11B show how messages are transmitted from a first service74′ to a second service 74″ in accordance with an embodiment of thepresent invention. Referring to FIG. 11A it can be seen that the firstservice 74′ comprises a plurality of service handlers 77′ which providethe functionality of the first service as described above. The firstservice 74′ additionally comprises an in queue IN1 into which incomingmessages are placed, and an out queue OUT1 into which outgoing messagesare placed prior to transmission. The second service 74″ comprises aplurality of service handlers 77″, an in queue IN2 and an out queueOUT2. Both the first service 74′ and the second service 74″ haveassociated with them unique addresses which are used for directingmessages to them.

FIG. 11B illustrates how messaging is effected using the structureillustrated in FIG. 11A. FIG. 11B illustrates routing of a message fromone of the service handlers 77′ of the first service 74′ to one of theservice handlers 77″ of the second service 74″. At step S1, a servicehandler 77′ of the first service 74′ executes the command specified inthe message. When this execution is complete, the service handler 77′interrogates the message to determine an address mask of the nextservice to which it is to be sent, and modifies the message to show thisaddress mask (step S2). At step S3, the message is sent to the out queueOUT1 of the first service 74′. A MessageDispatcher object associatedwith the out queue OUT1 then copies the message to its wait queue (stepS4), and interrogates the message to obtain an address mask indicatingthe message's intended destination (step S5). At step S6, aComponentRegistry object is used to locate all services within thecurrent operating system process which match the message's address mask.

At step S7, a check is made to determine whether or not any serviceshave been located. If it is determined that a single appropriate servicehas been located (e.g. the second service 74″ of FIG. 11B), the messageis forwarded to the in queue of that service (step S8), an appropriateservice handler is located within that service (step S9), and themessage is forwarded to the located service handler.

If step S7 determines that no suitable service can be found within thecurrent process, the message is amended to show that it must be directedto a messaging service which can carry out inter-process messaging (stepS11). An appropriate messaging service is then found (step S12), themessage is directed to the in queue of the messaging service (step S13)and the messaging service then carries out inter-process communication(step S14).

If step S7 locates N suitable services, where N is greater than one, acounter variable, m is initialised to zero, (step S15), and then asequence of operations are carried out N times by the action of a loopestablished by steps S16 and S21. Each loop will produce a clone of themessage (using standard Java functionality) at step S17 and this is sentto one of the located services at step 18, A suitable service handler isthen located within each service (step S19) and appropriate processingis carried out (step S20).

FIGS. 12A to 12D illustrate messaging in further detail.

Referring to FIG. 12A, it can be seen that a CommandExecutor object 77b′ (referenced by an appropriate variable in an appropriate handlerclass) uses an execute method provided by a command stored in a Commandvariable within a message 88 a′. In the example illustrated in FIG. 12Athe command is a ReceiveUserRequestCommand, which in turn is handled bya connection handler object 77 c′. It is at this stage that service andmessage specific processing takes place. Assuming that the command iscorrectly executed, the CommandExecutor object 77 b′ uses acommandSucceded method provided by the message 88 a′. It can be seenthat this method is provided by the AbstractMessage class (FIG. 8B), andall messages are instances of subclasses of the AbstractMessage class.In the case of a CommandSequenceMessage, the commandSucceded method willcause a CommandTargetPair variable m_ProcessingDelivery to be set to thenext command, and the next target address. When this is complete, aSendServiceMessage method provided by a ConnectionService object 74 a′is used to direct the message to the service's out queue (represented byan mOutQueue variable in the BaseService class), using a put method.Thus FIG. 12A illustrates the steps required to place a message in aservice's out queue.

Referring to FIGS. 8B and 8C it can be seen that aCommandSequenceMessage object comprises a command sequence (which is aninstance of a CommandSequence object, FIG. 8H), and threeCommandTargetPair objects. A first CommandTargetPair is set set in thecase of success as described above using the commandSucceded method. Asecond CommandTargetPair is set in case of failure by a commandFailedmethod, and a third CommandTargetPair is used where communication isrequired between processes, as is described below with reference to FIG.12D. State information within a message object is used to determinewhich of the CommandTargetPair objects should be used at a particulartime.

FIG. 12B illustrates steps which are carried out after a message hasbeen placed in a service's out queue. The out queue of the service isprovided with its own MessageDispatcher object 80′, which implements theThread interface provided by the Java programming language. A get( )method provided by a WaitQueue is called by a MessageDispatcher object80′. The get( ) method transfers the message to a queue represented byan mWaitQueue object 80 a′ within the Message dispatcher object 80′. TheMessageDispatcher object 80′ then locates an appropriate MasterNodeobject 55′, and routes the message to that node.

On receiving the message, the MasterNode object 55′ locates aRouterThread object 58′ from its pool of router threads (represented byan instance of a class implementing the Pool interface illustrated inFIG. 5D.), using a getRouterThread method. Having located a suitableRouteThread object, a route method provided by a RouterThread object 58′is used to route the message to the correct service. This involvescalling the getAddressMask method provided by the Message object toobtain an address mask, and then using a ComponentRegistry object 31′ tolocate all services matching the obtained address mask by calling afindLocalAddressables method provided by the ComponentRegistry object31′. Assuming that at least one suitable service is found, a getRouter() method is called on the Service object 74 b′. A route( ) methodprovided by the Service object 74 b′ is then used to route the messageto out queue 74 c′ of the Service object 74 b′.

If no suitable services are located by the findLocalAddressables method,the processing illustrated in FIG. 12D is carried out, as described infurther detail below.

If more than one service is found within a node which matches thespecified address mask, then the message is cloned and sent to the inqueues of all services in the manner described above. Furthermore, itshould be noted that as soon as the message is dispatched to theRouterThread object 58′ the work of the MessageDispatcher object isfinished, thus operation of the MessageDispatcher object 80′ isdecoupled from operation of the RouterThread object 58′.

FIG. 12C illustrates processing when a message has reached a service'sin queue. A MessageDispatcher object 80 b′ is associated with the inqueue and listens for message arrivals. When a message arrives, theMessageDispatcher object 80 b′ uses a get( ) method to copy the messageto its WaitQueue object 80 c′. A route method is then used to forwardthe message to a MessageToHandlerForwarder object 80 d′. TheMessageToHandlerForwarder object 80 d′ uses a getObject method providedby a ServiceHandlerPool object 80 e′, to provide a Handler object 77 d′.The MessageToHandlerForwarder object 80 d′ then call a handleMessagemethod (specified in the MessageHandler interface) to cause the messageto be handled. In due course the Handler uses a setNextCommand methodprovided by a CommandExecutor object 77 b′ to cause the command sequenceto be suitably updated.

FIG. 12D illustrates the processing shown in FIG. 12B, modified where itis the case that the RouterThread object 58′ determines that there areno services registered with the ComponentRegistry 31′ which match thespecified address mask. In this case, a leaveProcess method is used toupdate the internal state of the message object 88 a′, and theRouterThread then seeks to locate a service which is responsible forinter-process communication by using a getAddressMask method and afindLocalAddressables method, which will return an appropriate service74 d′. Having located an appropriate service the message is sent to thatservice in the manner described above with reference to FIG. 12B. Onreceipt of the message an the In queue of the service, the servicehandles the message (as described with reference to FIG. 12D), andinter-process communication is thus achieved.

From the preceding description, it can be seen that message routing iscarried out as specified within appropriate variables of a givenmessage. There is no central control of message routing, but insteadcontrol is distributed between objects which handle messages.

For example, referring to FIG. 13, there is illustrated a system of fivemessage handlers denoted A, B, C, D and D′. The message handlers D andD′ are both instances of a common message handler.

A message Msg1 is sent from handler A, to handler B, and subsequentlyfrom handler B to handler C. Handler C processes Msg1 in a predeterminedmanner, and generates two messages, Msg2 and Msg3. Each of thesemessages is then routed independently. The message Msg2 is routed tohandler D while the message Msg3 is routed to the handler D′.

Each handler processes the message, and routes the message onwards tothe next service specified therein. Distributing control of messagerouting in this way provides a scalable system, and removes the need forany centralised control of messaging. This is particularly beneficialwhere a handler creates a plurality of messages from a single receivedmessage (as in the case of handler C in FIG. 13).

Referring back to FIG. 2, having described a framework for operation ofthe server 13. operation of the webserver 12 and server 13 to providecomposite user interfaces is now described.

FIG. 14 illustrates the logical architecture of the web server 12 andthe server 13. It can be seen that the server 13 operates using aprocess framework as illustrated in FIG. 3, and comprises a Host MasterWatchdog process 100, a Host Master process 101 and a process 102.

The process 102 comprises a process Agent 104 and a Node Manager 105which perform functions as described above. The process 102 comprisesthree nodes 106, 107, 108. A client adaptor (CA) node 106 is responsiblefor interaction between the server 13 and the composite application(s).An application adapter (AA) node 107 is responsible for interactionsbetween the server 13 and the appropriate source applications via asource application interface 109. An ALF (Authentication LockdownFramework) node 108 is responsible for authentication and securityfunctionality provided by the server 13. Security information is storedin a database 110 which is accessed via a conventional Java DatabaseConnectivity (JDBC) interface 111. The function of each of these nodesis described in further detail below.

The server 13 is connected to an administration terminal 112 via a link113. The administration terminal 112 allows administrators of the server13 to perform various administration functions, as described below.

Configuration data for the nodes 106, 107 is obtained from anIntegration Data Manager (DM), which comprises a database 115 accessedvia an appropriate interface (such as JDBC interface 116). The form ofthe configuration data, and the manner in which it is used is describedin further detail below. It should be noted that the database 110 andthe database 115 together make up the configuration data 18 of FIG. 2.

The Webserver 12 communicates with the server 13 via a connection 14.The webserver runs a Java™ servlet 117, and this servlet 117 isresponsible for communication between the webserver 12 and the server13. In many situations is necessary to impose restrictions on access tocomposite applications or parts of composite applications managed by theserver. Such restrictions can be conveniently implemented by allocatinguser names and passwords to users, and associating appropriate accessprivileges with such usernames and passwords. The servlet 117 implementsany necessary security policies, by cooperating with the CA node 106.The functionality provided by the servlet 117 is referred to as a UserAgent (UA) service.

The CA node 106 comprises four services. A Messaging layer (ML) service118 provides Java Messaging service (JMS) functionality forcommunication between objects within different processes. The JMS issuch that messaging between processes can be carried out in a unifiedmanner, regardless of whether processes are located on the same ordifferent hosts.

A Communications Layer (CL) service 119 provides connections between theCA node and other processes. A Data Transformation (DT) service 120provides means to transform data from one form to another. Such aservice can be required both when receiving user data from a compositeapplication which is to be forwarded to a source application, and whenreceiving data from one or more source applications which is to beoutput to a composite application. A User Experience Manager (UXM)service 121 is responsible for determining the action necessary whenrequests are received from the webserver 12, and when data is receivedfrom a source application.

The AA node comprises three services an ML service 122, a CL service 123and a DT service 124. Each of these services provides the samefunctionality as the equivalent service of the CA node 106.

The ALF node 108 again comprises an ML service 125 and an ALF service126. The ALF service 126 is responsible for security features as isdescribed in further detail below.

The use of the CA node 106 and the AA node 107 to produce and managecomposite applications is now described with reference to FIG. 15. Auser operates a web browser 126 to access HTML documents provided by theweb server 13 which make up a composite user interface. A user issues arequest via the web browser 126. This request is forwarded to thewebserver 12 using the Hyper Text Transfer Protocol (HTTP) operating ina conventional manner. The servlet 117 within the web server 12 operatesa UA service 127. The UA service 127 authenticates the request inaccordance with predetermined security policies (defined as describedbelow). If the authentication is successful, an IncomingUserRequestmessage is created using parameters received by the UA (e.g. from theHTTP request). This IncomingUserRequest message is then sent by the UAservice 127 to the server 13, having a target address of the CL service119 of the CA node 106. As described above, this message is transmittedusing the JMS protocol. The CL service 119 receives theIncomingUserRequest message, and having received the message, directs itto the DT service 120 of the CA node 106. The DT service 120 performsany necessary transformation of data contained in theIncomingUserRequest message, and directs the message onwards to the UXMservice 121 of the CA node 106. The UXM service 121 processes themessage and generates one or more OutgoingUserRequest messages, destinedfor the appropriate source application(s) 128. These messages are firstsent to the DT service 124 of the AA node 107 using, for example, theJMS protocol.

The DT service 124 of the AA node 107 performs any necessarytransformation, and forwards the message to the CL service 123, which inturn generates messages to request appropriate data from the sourceapplication(s) 128 in an appropriate format. These messages are thenforward to the Source Application(s) using, for example, the JMSprotocol.

The Source application(s) 128 process received messages and in turnproduce data in response to the received request. This data is receivedby the AA node 107, and passed to the CL service 123. The data is thenforwarded to the DT service 124 which processes the data to extract oneor more page objects and to create an IncomingUserResponse message whichis forwarded to the UXM service 121 of the CA node 106.

The UXM service 121 processes the IncomingUserResponse message, anddetermines whether or not it has received all data necessary to create acomposite page (determined by its configuration, which is describedbelow). When all data required is received, an OutgoingUserResponsemessage is created which is forwarded to the DT service 120 where anynecessary transformation is carried out. Having performed any necessarytransformation the OutgoingUserResponse message is forwarded to the CLservice 119 and then onwards to the ML service. The ML service transmitsthe composite page to the UA 127 using the JMS protocol. The UA thendisplays the page to the user via the web browser 126, assuming that anynecessary validation is successfully carried out by the UA 127.

In the description presented above, a distinction is made betweenIncomingUserRequest messages and OutgoingUserRequest messages. A similardistinction is made between IncomingUserReponse messages andOutgoingUserResponse messages. These distinctions are made to aidunderstandability, however it should be appreciated that in someembodiments of the invention both IncomingUserRequest messages andOutgoingUserRequest messages are represented by a single UserRequestmessage type. Similarly both IncomingUserReponse messages andOutgoingUserResponse messages may be represented by a singleUserResponse message type.

It will be appreciated that the processing described above can be usedto handle a wide range of different composite applications, however itwill also be appreciated that the processing required will varyconsiderably, and therefore an effective means of configuring theservices illustrated in FIGS. 14 and 15 is required. This is achieved byaccessing the IDM database 115. IDM data is stored in a hierarchicalmanner as will be described in further detail below.

At startup, the web server 12 and the server 13 need to be provided withdata which allows access to the IDM database, and indicates where inthat database the appropriate data is located. This is achieved byproviding each with appropriate invocation parameters which indicatewhere the configuration data can be located.

The servlet 117 of the webserver 12 (referred to as “the listener”) isprovided with invocation parameters as illustrated in FIG. 16.

A g2jms.config parameter specifies a file containing JMS configurationproperties for the servlet 117. A g2config.home parameter specifies adirectory containing an IDM properties file, which provides informationas to how the IDM database 115 is accessed. A g2listener parameterspecifies a node in the hierarchical IDM data structure whereconfiguration information for the UA service 127 is located. Ag2config.instance parameter species configuration data for the compositeapplication which the webserver 12 is to provide to a user. Ag2jms.config parameter specifies configuration for the JMS service ofthe UA 127. A g2tracer.conf parameter specifies logger configuration.

The nodes and services of the server 13 (collectively referred to as“the composer”) are provided with invocation parameters are illustratedin FIG. 17.

The g2config.home, g2jms.config and g2config.instance parameters performfunctions as described with reference to FIG. 16. The g2config.webhostparameter specifies an IP address for the web server on which the UAservice 127 is implemented by means of the servlet 117. Theg2config.baseipport parameter specifies a port number used by anadministration console which is used in connection with the composer asdescribed below. The g2basetracer.conf parameter is used to specify alog file for each process operating within the composer. Given thatevery composer comprises at least a HostMaster process and a processcontaining AA and CA nodes, at least two log files must be specified, inaddition to a log file for the web server.

The parameters described above with reference to FIGS. 16 and 17together allow the listener and the composer to obtain configurationdata from the IDM. Additional invocation parameters are illustrated inFIG. 18. These specify page tags which are used in HTTP requests passedto the listener by the composer.

APPLICATION_CLASS specifies a name used for the composite application,and is used by the composer to determine any transformation that theCA.DT may be required to perform. UXM_TREEID and UXM_NODEID specifywhere in the configuration the UXM can find configuration informationpertinent to the specific composite page. UXM_MODIFIED allows the UXM toperform no processing on some pages. If UXM_MODIFIED is set to true,this is an indication that processing is required in accordance with theconfiguration data stored in the IDM (described below). If UXM_MODIFIEDis set to false, this means that no processing is required and the UXMsimply forwards the message to the AA node.

Additional tags are used for security purposes. A g2authorization tag isused to indicate that the listener should attempt authentication. usrand pwd tags are respectively used to represent user name and passworddata when this is required for authentication.

The invocation parameters described above allow the composer and thelistener to locate the IDM and to locate suitable data within the IDM.These parameters are conveniently implemented as variables ofappropriate Java classes. They can be configured by means of asystem.properties file, an example of which is illustrated in FIG. 19.Each line of the file corresponds to a Java property to be set. It canbe seen that all entries of the file are prefixed by either ‘hm’ or‘pa’. This ensures that each entry is picked up by the correct process.Entries prefixed by ‘hm’ are picked up by the HostMaster process, and itcan be seen that these correspond to the composer invocation parametersdescribed above. Entries prefixed by ‘pa’ are additional properties tobe set in each process set up by the HostMaster process. These typicallyinclude configuration for various aspects of the Java Virtual Machine(JVM) such as garbage collection.

It can be seen that in FIG. 19, all entries which begin ‘pa’ are of theform ‘pa.x’. This indicates that the property should be set on allprocesses started by the HostMaster. However, in some embodiments of theinvention entries may be prefixed by ‘pa.N’ where N is an integer. Inthis case, that entry refers only to process N.

It should be noted that the system.properties file is used in ahierarchical manner as follows. Any entry of the form ‘pa.N’ willoverride a ‘pa.x’ entry for process N. Any entry of the form ‘pa.x’ willoverride the ‘hm’ entry inherited from the HostMaster process. Inaddition to setting parameters by means of the system.properties file,it should be noted that configuration parameters can be specified atstart up, for example via a command line interface. In such a case, if aproperty value is specified both in the system.properties file and onthe command line, the system.properties file will determine the value.

Having described invocation parameters, and associated tags, thestructure of IDM data stored in the database 115 is now described.

It should be noted that, as will become apparent below, every compositeapplication has a unique application class name which is used toidentify it. Every source application also has an unique applicationclass name which is used for identification. Thus, if a compositeapplication is made up of two source applications, its configurationwill include three application class names.

A partial IDM structure for a configuration containing a single processcontaining an AA node and a CA node (as illustrated in FIG. 14) is shownin FIG. 20. The highest level of the hierarchy comprises a single entityCONFIG 129 which is the root of the IDM tree. This entity has six childentities. An entity INSTANCE 130 is concerned with configurationinformation for a particular composer configuration. An entityBASE_ALF_CONFIG 131 provides configuration information for an ALF node.Entities HOST 132, PROCESS 133, NODE 134, and SERVICE 135, each havechildren containing configuration information for the correspondingentities of FIG. 14.

As described above, the g2instance parameter references a named node inthe IDM that contains appropriate configuration data. This data willinclude details of the number of processes that should be used, theallocation of CA nodes, AA nodes and ALF nodes to those processes, andlocations where data appropriate for the services contained within thosenodes can be found.

In this case the g2instance invocation parameter is set such that:

g2instance=LAB1_INS

This indicates that the composer should locate the LAB1_INS entity 136which is a child of the SINGLE_PROC_AA_CA_INSTANCE 130 a, which isitself a child of the instance entity 130 a to obtain configurationdata. It can be seen that the LAB1_INS entity has suitable data providedby a g2config data group 137.

The entry alf in the data group 137 indicates that server uses the ALF,and provides means for locating the ALF database 110 (FIG. 14). Theentry host indicates that the server 13 comprises a single hostreferenced by that entry in the data group 137. It can be seen that allother entries are of the form “host.process1.”. Each of these entriesprovides details of a respective node or service operating within thesingle process 102 (process1), on the server 13 of FIG. 14. It can beseen that every node and service illustrated in FIG. 14 has acorresponding entry in the data group 137, which provides details of itsconfiguration.

Configuration of the CL service 123 of the AA node 107 (FIG. 14) is nowdescribed. FIG. 21 shows part of the hierarchy of FIG. 20 in furtherdetail, together with details of entities relevant to the configurationof the CL service 123 of the AA node 107. In addition to the entitiesdescribed above, the hierarchy comprises a BASE_CL_SERVICE entity 138which is a child of the SERVICE entity 135. The BASE_CL_SERVICE entity138 has two child entities, a AA_CL_SERVICE entity 139 which representsthe CL service 123 of the AA node 107, and an EXT_APPS entity 140 whichcontains details of relevant source applications. It should be notedthat the hierarchical arrangement of the IDM allows child entities toinherit and override properties of their parent entity. For example,default data for all services may be specified in the SERVICE entity135. Some this data may be inherited and used by the BASE_CL_SERVICEentity 138, while other parts of the data may be replaced by moreappropriate values specified in the BASE_CL_SERVICE entity 138.

It can be seen that the host.processxAA.CL entry in the data group 137references a data group g2config 141 under a mysrcapps entity 142. Theg2config data group 141 includes an entry for every source applicationwith which the AA communicates, and each application is referenced byits application class name. Each entry will include a session timeoutparameter which indicates a time (e.g. in minutes) which a user can beinactive without a connection being terminated, and a replicate_sessionsparameter which is a Boolean indicating whether or not session datashould be copied between processes. Setting this parameter to TRUEprovides fail over if session data is lost for any reason.

The source applications from which the composite application is createdare each represented by a child entity of the EXT_APPS entity 140. InFIG. 21, two source applications are illustrated. A first sourceapplication (having a class name “SrcApp1”) is denoted by an entitySrcApp1 143 and a second application (having a class name “SrcApp2”) isdenoted by an entity SrcApp2 144.

Each of these entities has two data groups. The SrcApp1 entity 143 has ag2config data group 145 which is referenced by the data group 141 andwhich specifies data for the configuration of the AA, and a connectiondata group 146 which specifies communications protocols forcommunication with the SrcApp1 application. The entity SrcApp 2 144 hastwo similar data groups 147, 148.

The data stored in relation to each source application is now described.The g2conifg data group for each source application 145, 147 includes anumber of parameters. An authorization parameter takes a Boolean valueand indicates whether or not the source application requiresauthentication. A credential_type parameter is required when theauthorization parameter is set to TRUE. The credential_type parameter iseither set to USRPWD or DYNAMIC. When creditial_type is set to USRPWD, astatic username, password combination is used for authentication. Whencredential type is set to DYNAMIC, a static username and dynamicallycreated password is used for authentication. For example, a password canbe dynamically created from a user name using a predetermined algorithm.A protocol parameter indicates a protocol to be used for communicationwith the source application. Suitable protocols may include HTTP, SOAP,MQSERIES and JDBC. Other parameters provide information as to how errorsshould be handled.

The connection data group associated with each source application 146,148 stores information related to each connection. It can be seen fromFIG. 21 that the connection data groups are not directly referenced bythe g2config data group 141, and are located by virtue of the fact thatthey are located below the same entity as the g2config data group 145,146 for each application.

Each connection data group 146, 148 will include indications of aprotocol to be used, a port number of the source application to whichdata should be sent, an identifier for the host on which the sourceapplication is operating, a proxy identifier (if appropriate), togetherwith parameters related to session refresh and logout.

In addition to the parameters described above, the connection data groupwill include various other parameters appropriate to the protocol beingused.

If SOAP is being used these parameters will include a file part of a URLto use for connection, a URI style for message encoding, a URI for thetarget object, and a URI indicating the intent of the SOAP request.

If JDBC is being used, these parameters will include a URL for JDBCdatabase connection, a JDBC driver name, and parameters indicating bothinitial and maximum JDBC connection pool sizes.

Other protocols will require other parameters, and such parameters willbe readily apparent to those of ordinary skill in the art.

In addition to the data set out above, various other configuration datamay be used to configure the CL service of the AA. Such configurationdata may either be stored in one of the data groups described above, oralternatively may be stored in an additional data group. Typically, suchadditional data groups are located within the same source applicationentity 143, 144 as the data groups described above, and accordingly theinstance entity 136 is able to locate all necessary configuration data.

The CL service 119 of the CA node 106 (FIG. 14) is configured in asimilar manner, although it will be appreciated that in this case, dataof a similar form will be required for the or each composite applicationinstead of the source applications. In some embodiments of the IDM, thedata group 141 includes an entry for each composite application inaddition to entries for each source application, and these entries inturn identify appropriate entities located below the EXT_APPS entity140.

Configuration data for the DT service 120 of the CA node 106, and forthe DT service 124 of the AA node 107 is now described. FIG. 22 is atree diagram showing part of the hierarchy of FIG. 20, together withdetails of entities pertinent to configuration of the DT services.

The service entity 135 has a child entity 149 BASE_DT_SERVICE which inturn has a child entity DT_SERVICE 150 which represents all DT serviceconfiguration data. An entity LAB1_DT 151 is a child entity ofDT_SERVICE and represents DT service configuration for the applicationrepresented by the LAB1_INS entity 136.

It can be seen that the host.process1.AA.DT and host.process1.CA.DTentries in the data group 137 both reference a DT.service data group 152which is located beneath the Lab1_DT entity 151. The DT.servicedatagroup contains a single entry which allows it to locate its parententity.

A DT.Applications data group 153 is located under the same entity 151 asthe DT.service data group 152. The DT.Applications data group 153contains one entry for each composite application which must be handledby the DT service of the CA, and one entry for each source applicationwhich must be handled by the DT service of the AA. In the example ofFIG. 22, it can be seen that the data group 153 includes an entry for asingle composite application Lab1App, and a single source applicationfirstbyte. FIG. 22 shows data needed to configure the DT service of theCA to handle the composite application Lab1App.

It can be seen that the Lab1App entry in the DT.Applications data group153 references a DT.AppLab1App data group 154 which contains datarelevant to handling transformations to and from the compositeapplication Lab1App. The DT.App.Lab1App data group 154 includes an entryindicating transformations required in response to anIncomingUserRequest, an entry indicating transformations required inresponse to an OutgoingUserRequest, and en entry indicatingtransformations required to convert data from the UXM in a form suitablefor output to the composite application.

The UXM entry references a DT.App.Lab1App.UXM data group 155 which inturn contains entries which indicate how data should be transferredbetween UXM objects used in the UXM of the CA, and data which can beprocessed by the composite application. In the example of FIG. 22, thedata group 155 includes a NewObjectTransformations entry whichreferences a data group 156 and a UIElementTempates which references adata group 157. This data allows new data to be added to data receivedfrom source applications to create a composite page. TheUIElementTemplates data group 157 contains details of such new data, andthe NewObjectTransformations data group indicates how this data shouldbe included in a composite page.

It can be seen that the other entries in the DT.App.Lab1App data groupreference other data groups 158, 159, 160 which contain data indicatinghow these transformations should be carried out.

FIG. 23 shows part of the IDM data structure which holds data pertinentto the DT service of the AA node. It can be seen that the firstbyteentry in the DT.Applications data group 153 references aDT.App.firstbyte data group 161, which includes an entry for each datatype which the DT service of the AA may be required to handle, that isIncomingUserRequest, OutgoingUserRequest, IncomingUserResponse,OutgoingUserResponse, and UXM objects. It should be noted that althoughin the example of FIG. 15 only OutgoingUserRequest andIncomingUserResponse messages are processed by the DT service of the AA.However, IncomingUserRequest and OutgoingUserResponse messages areincluded for the case where the composer simply passes messages betweena composite application and a source application without carrying outany processing.

It can be seen that the entries in the DT.App.firstbyte datagroup 161relating to the four message types reference appropriate data groups162, 163, 164, which contain the necessary transformation information.The UXM entry references a DT.App.firstbyte.UXM data group 165, whichincludes four entries. An ErrorPageResolverData entry references aDT.App.firstbyte.UXM.ErrorPageResoverData data group 166 which containsmeans to recognise various error pages which may be generated by thefirstbyte source application. A PageResolverData entry references aDT.App.firstbyte.UXM.PageResolverData data group 167 which contains dataindicating how pages of the source applications are recognised, in orderto identify necessary transformations. A PageExtractionConfig entryreferences a DT.App.firstbyte.UXM.PageExtractionConfig data group 168which contains references to a plurality of Extensible Markup Language(XML) files, which indicate how each page recogniser by an entry in thePageResolverData data group should be transformed by the DT servicebefore being passed to the UXM service of the AA.

Configuration data for configuring the UXM service 121 of the CA node106 is now described with reference to FIG. 24, which shows the relevantparts of the IDM data structure. The highest level of the illustratedtree structure is a BASE_UXM_SERVICE entity 169 which is a child of theSERVICE entity 135 (FIGS. 20 to 23). The BASE_UXM_SERVICE entity 169 hasthree child entities, a CA_UXM_SERVICE 170 which represents datarelevant to the UXM service 121 of the CA node 106 (FIG. 14), AUXMActionLibrary entity 171 which stores UXM action data, and aUXMPredicateLibrary entity 172 which stores predicate data.

The CA_UX_M_SERVICE entity 170 has a child entity named TreeRootNode foreach composite application which the UXM is able to handle, and anadditional entity 173 to deal with error conditions. A TreeRootNodeentity 174 represents a first composite application CompApp1, while asecond TreeRootNode entity 175 represents a second compositeapplication. Each TreeRootNode entity 173, 174, 175 has a control datagroup which specifies a unique identifier. In the case of the data group176 associated with the entity 173, this identifier is simply “error”,while in the case of the data groups 177, 178 an appropriate identifieris set. The control data groups additional include information which canbe used to limit a particular nodes usage. Under the TreeRootNode 174which relates to CompApp1, there are two child TreeNodes which eachrepresent different pages of the composite user interface for CompApp1.A first child TreeNode 178 and its associated data group represent apage customer page CustPg, while a second child TreeNode 179 and itsassociated data group represent an order page OrderPg. It can be seenthat the TreeNode 178 in turn has three child TreeNode entities 180,181, 182, each of which represent particular parts of the customer page.

It was indicated above that the identifier within the control data groupfor each composite application must be unique. It should be noted thatwithin a particular application, all identifiers must be unique withinthat application.

FIG. 25 shows an alternative view of the tree structure of FIG. 24. Itcan be seen that in addition to the control data groups described above,All TreeRootNode entities 174, 178, 180, 181, 182 additionally includean integration data group 183 which specifies the actions to be taken,if any, when a composite application of the type represented by theTreeRootNode 174 is encountered. This information is determined by datastored in a library located under the UXMActionLibrary entity 171.

Additionally, the TreeRootNode entities 178, 180 comprise a predicatesdata group which specifies conditions (or predicates) which need to betrue for the actions specified in the integration data group to betaken. Each of these predicate data groups references a predicatelibrary located under the UXMPredicateLibrary entity 172.

FIG. 26 shows part of the UXM configuration for a composite applicationLab2App represented by a TreeRootNode entity 183. It can be seen thatthe TreeRootNode entity 183 has a control data group 184 and anintegration data group 185. A TreeNode 186 specifies UXM data for partof the Lab2App application, and has a control data group 187 and anintegration data group 188. The integration data group specifies actionsto be taken in response to particular events, and these actions arespecified in terms of an appropriate data group. For example, an entryfor an action deleteUXMObj.1 references aDeleteUXMObjectFromTagetConext.RemData data group 189 within an actionlibrary Lab2_Lib 190 for the Lab2App application. Similarly anaggregateNews.2 entry in the integration data group 188 references anAggregateNamedContexts.AggregateNews data group 191 in the Lab2_Liblibrary 190. In turn, this data group references two TreeNodes 192, 193which are child entities of the TreeNode entity 186. The other entriesin the integration data group 188 reference corresponding entities 194,195 in the Lab2_Lib library 190. Operation of the UXM in accordance withthe configuration data described above is set out in further detailbelow.

Configuration of the ML services of the CA node 106 and the AA node 107(FIG. 14) is now described. As indicated above, communication betweenprocesses is accomplished using JMS, and the JMS protocol isencapsulated within the ML services. Referring back to FIG. 20 it can beseen that ML entries of the g2config data group 137 reference anappropriate g2config data group 196, located beneath an ML_SERVICE 197which is itself located beneath a BASE_ML_SERVICE entity 198. For themost part, configuration of the ML is based upon properties files, notby data within the IDM. These files can be located using invocationparameters, as described above with reference to FIGS. 16 and 17. The MLis configured using properties files instead of IDM data because much ofthe configuration is required at start up, before the IDM has beenaccessed. In preferred embodiments of the invention, a commonconfiguration is shared by the CA node 106 and the AA node 107. JMSmakes use of the Java Naming and Directory Interface (JNDI) to obtainnecessary information. The properties files must therefore containdetails which allow connection to the JNDI. Additionally, the propertiesfile must include parameters which specify all necessary configurationdata for the JMS implementation used to put embodiments of the inventioninto effect. In preferred embodiments of the present invention, theSunONE MQ3.0 JMS implementation or the OpenJMS 0.7.2 implementation areused Configuration data required will be well known to those skilled inthe art, and is not described in further detail here.

However, it should be noted that some configuration parameters used inpreferred embodiments of the present invention provide beneficialresults. For example, it should be noted that each process within thesystem can send broadcast messages using a broadcast topic. Each processwill have a single in queue and a broker will manage these queuesensuring that any message is sent to the in queues of all relevantprocesses. Additionally, each process has a persistence queue, intowhich messages are delivered if the in queue is unable to acceptmessages for any reason. This queue provides failover for the system.

Having described configuration of all services of the CA node 106 andthe AA node 107 (FIG. 14), configuration of the ALF service 126 of theALF node 108 is now described. ALF configuration data is stored in thehierarchical IDM data structure, as illustrated in FIG. 27. The g2configdata group 137 for the entity Lab1_INS 136 references a g2config datagroup 199 located beneath the BASE_ALF_CONFIG entity 131. The g2configdata group 199 provides the information necessary to allow the ALFdatabase 110 (FIG. 14) to be located. It can be seen that this datagroup includes details of a url for the database, a driver to be usedwith the database (here the Oracle™ JDBC driver) and user name for usewhen logging onto the database 110. It will be appreciated that otherdata may be required in order to properly access the database 110 andthis too will be stored in the g2config data group 199.

Each user who is authorised to use a composite application will have auser entity 200, 201 which is a child of the BASE_ALF_CONFIG entity 131.The user entity 200 has a G2 data group 202 which includes a user nameused by that user when logging on to composite applications provided bythe composer. Additionally, the user entity 200 has a SrcApp data group203 which includes details which are needed to log on to a sourceapplication “SrcApp”. A similar data group is provided for each sourceapplication which a user is able to access. The user entity 301 has a G2data group 204, and will also comprise one or more entries forappropriate source applications (not shown).

The BASE_ALF_CONFIG entity 131 also has a usersconfig data group 205which specifies details relating to logging onto to the compositeapplication, for example password format, and a frequency with whichpasswords must be changed. The values specified in the usersconfig datagroup 205 provide a default log on configuration, which is inherited byall user entities. However, this default configuration may be overriddenby a usersconfig data group located below an appropriate user entity. Itshould be noted that similar information relating to each sourceapplication is stored as part of the configuration of the CL servicewithin the AA node.

The BASE_ALF_CONFIG entity 131 has an additional child entityCONSOLE_CONFIG 206. This entity comprises a plurality of data groups(not shown) which state how configuration data input to the system viathe administration terminal 112 (FIG. 14) is converted to ALF commands.Commands are typically received from the web browser basedadministration terminal 112 as HTTP requests, which are mapped toappropriate ALF commands. The administration terminal 112 is used to addusers and perform other necessary administration functions related tothe ALF.

Referring back to FIG. 20, it can be seen that the host.process1.ALFNODEentry in the g2config data group 137 references a g2config data group206 located beneath BASE_ALF_ML_NODE 207. The host.process1.ALFNODE.ALFentry in the g2config data group 137 references a g2config data group208 located beneath a BASE_ALF_SERVICE entity 209. The g2config datagroup 208 will allow access to the ALF database identified by theg2config data group 199 located beneath the BASE_ALF_CONFIG entity 131.

Having described configuration of all services contained within thenodes of the server 13, configuration of the listener provided by theweb server 12 is now described. As indicated above, a g2listenerinvocation parameter specifies an entity within the IDM which is usedfor listener configuration. FIG. 28 shows an appropriate IDM datastructure. In this case, the g2listener parameter is set such that:

g2listener=weblistener;

That is, the listener would locate a weblistener data group 210 locatedbeneath a UAconfigs entity 211. The weblistener data group 210 indicatesto where incoming requests should be directed (usually a CA service),and the name of a Java class providing authentication functions (in thiscase custom). The weblistener.custom data group 212 provides a mappingfrom request parameters to those needed for authentication.

It will be appreciated that means must be provided such that appropriateconfiguration data can be entered into the IDM database, to create thehierarchies described above. Specification of this configuration data isnow described using a predetermined file format.

FIG. 29 shows a file which can be used to configure the CL service 119of the CA node 106. Text shown in square brackets “[ ]” denotes anentity names within the IDM hierarchy. Text shown in triangular brackets“< >” denotes a name of a data group which is positioned beneath theappropriate entity within the IDM hierarchy. Text shown in curlybrackets “{ }” denotes a parameter type. “{GRF}” indicates that aparameter is a reference to another data group. A {GRF} parameter isfollowed by an appropriate entity name and data group name to which itrefers. “{STR}” indicates a string parameter. Parameters specified by“{INT}” and “{BLN}” can also be used, although these are not shown inFIG. 29. “{INT}” indicates an integer parameter, and {BLN} indicates aBoolean parameter.

Referring to FIG. 29, it can be seen that the file specifies a CONFIGentity, having a SERVICE entity as a child, which in turn has aBASE_CL_SERVICE entity has a child. A CA_CL_SERVICE entity is a child ofthe BASE_CL_SERVICE entity, and has a LAB1_SrcApps entity as a child.The LAB1_SrcApps entity has a single g2config data group which comprisesa single group reference entry which references a g2config data grouplocated beneath a FirstByte entity within the hierarchical datastructure.

The file of FIG. 29 also specifies that the BASE_CL_SERVICE also has anEXT_APPS entity as a child entity, which in turn has a FirstByte entityas a child. The FirstByte entity has a single g2config data group whichspecifies two parameters of type string which provide authorization andprotocol information relevant to the FirstByte application.

Having described configuration of the architecture shown in FIG. 14,operation of services illustrated in FIG. 14 is now described.

The UXM service 121 is responsible for receiving user requests, andgenerating one or more source application requests in response to theuser request. The UXM service 121 is also responsible for creatingcomposite pages.

It should be noted that the UXM uses an internal data format ofUXMObjects to represent composite user interfaces and parts of suchcomposite user interfaces. Using UXMObjects in this way allows the UXMservice to operate in a manner independent of output format, andaccordingly adds considerable flexibility to the system.

A UXMObject stores unstructured data, as well as attributes describingthat data. A tree of UXMObjects is used to represent data for acomposite user interface. It can be recalled that the structure of thecomposite application is described by UXM configuration data within theIDM database (see FIGS. 24 and 25). The tree of UXM objects willtypically correspond to the tree structure for the UXM within the DDM,although it is important to note that the two trees are separate datastructures which are stored separately.

A UXM object includes unstructured data for a particular entity withinthe UXM tree of the IDM database, which represents part of a compositeuser interface. This data is typically stored using an array of bytes.Each UXMObject also has a mode parameter and a type parameter. The modeparameter is used to indicate where within a composite document aUXMObject should be placed relative to other UXMObjects. The modeparameter can therefore take values such as before, after, replace,insert and toplevel. The type parameter is used to differentiateUXMObjects created by the UXM service from UXMObjects created fromsource application data. UXMObjects can therefore have types of New andExisting. Each object additionally includes a set of attributes whichare associated with the unstructured data, and which either describe thedata, or are used for data conversion. Each UXM object has a identifier(which can conveniently correspond to an ID within the UXM tree withinthe IDM, see FIG. 24), and references to parent and/or child objects ifappropriate. These references to parent and/or child objects allow theUXMObjects to be used to create a UXM object tree. It should be notedthat UXMObjects may also contain nested UXMObjects.

During operation, the UXM maintains a UXM tree (separate from the UXMobject tree) which is based upon the configuration data stored in theIDM. This tree includes the actions, predicates and parameters which arepresent within the relevant entities and data groups of the IDM.Additionally, each entity within the UXM tree includes a state for eachuser at that node, which corresponds to a user's context.

The context for a user at a particular entity within the UXM tree willhold a state appropriate for that user for all requests which that usermay make and all response which that user may receive. This is stored asa set of parameters (typically as NVPs), and by reference to a singleobject within the UXMObject tree.

In summary, it can be seen that the UXM essentially uses three datastructures, the IDM data structure, the UXM tree and the UXMObject tree.

Information indicating how the UXM should operate in response to variousrequests and responses is configured within the IDM tree which atruntime is used to create the UXM tree. In addition to this information,the UXM tree also stored information relating to state of a particularuser at a particular node is stored at a user's context at a particularentity within the UXM tree. Data pertaining to particular pages of thecomposite user interface is stored within a UXM object, and UXM objectscollectively form a UXM object tree, which is separate from both the UXMtree and the IDM data structure. It can be deduced that for every entryin the UXM object tree, there must exist an entity in the UXM treehaving the same identifier. The converse is not necessarily true.

FIG. 30 shows a schematic illustration of part of a UXM tree 220 and aUXMObject tree 221. It can be seen that each entity in the UXM tree 220includes context information for User 1 The context data associated witheach entity in the UXM tree 220 includes reference (denoted by a brokenline) to an appropriate instance of a UXMObject in the UXMObject tree221. It can be seen that the UXM tree 220 and the UXM Object tree 221have the same structure. It will be appreciated that in many embodimentsof the present invention respective context data will be stored for aplurality of users, and each of the plurality of users will have arespective UXM object tree.

When describing the IDM data structure, it was explained that actionswere executed if predicates were satisfied. Predicates which may appearin predicate data groups within the IDM are now described.

Some predicates are based on a user's log on credentials. Users may beallocated to one of a plurality of roles, and aRoleAuthorisedGuardCondition predicate entry specifying a particularrole may be included in a predicate data group. This predicate will besatisfied only if a user's role matches the specified role. Similarly aRoleNotAurthorisedGuardCondition is satisfied only if a user's role doesnot match that specified by the predicate.

Some predicates are based on a NVP within a user's context at a givenentity within the UXM tree. A CompareNVPValueGuardCondition predicatecompares a specified NVP at a specified entity within the UXM tree witha specified NVP at a different entity within the UXM tree. The predicatehas a parameter indicating whether it should should evaluate to TRUE forequality or inequality.

A RegexNVPMatchGuardCondition predicate takes a regular expression as aparameter, and evaluates to true if a specified NVP at a specifiedentity within the UXM tree matches the regular expression.

An NVPEqualsGuardCondition predicate checks a value of a specified. NVPin a user's context at the current entity against a value specified as aparameter, and evaluates to TRUE in the case of equality. AnNVPNotEqualsGuardCondition predicate performs the opposite function toan NVPEqualsGuardCondition predicate—that is it evaluates to TRUE in thecase of inequality.

An NVPExists predicate checks if a specified NVP exists within theuser's context at the current entity within the UXM tree. If the NVPdoes exist, the predicate evaluates to TRUE. An NVPNotFound fulfils theopposite function to an NVPExists predicate, that is, it evaluates toTRUE if a specified NVP does not exist at the current node.

Various other predicates can also be specified. ARemoteServiceCredentialFound-GuardCondition predicate determines whethera user's context at a specified entity within the UXM tree includes logon credentials for a specified external system (e.g. a sourceapplication). If the service credential exists, the predicate evaluatesto TRUE. A RemoteServiceCredentialNotFoundGuardCondition predicateperforms the opposite function, that is it evaluates to TRUE if a user'scontext at a specified node does not include a service credential forthe specified external system.

ExternalIDs are used by the UXM to identify data elements withinexternal applications, such as source applications. Some actionsprovided by the UXM are concerned with creating and using ExternalIDs.The UXM maintains mappings between ExternalIDs, and internal IDs usedwithin the IDM.

An ExternalIDFoundGuardCondition predicate evaluates to TRUE if a user'scontext at a specified node includes a specified ExternalID. AnExternalIDNotFoundGuard-Condition predicate evaluates to TRUE if thespecified ExternalID is not found. A NodeGuardCondition takes aplurality of entity ID's as a parameter, and evaluates to TRUE if the IDof a specified entity matches one of the plurality of specified IDs.

A DataReady predicate checks if data (usually an UXMObject) is presentat a specified entity within the UXM tree. This predicate is used toensure that data necessary for aggregation (see below) is present at agiven entity within the UXM tree.

A FalseGuardCondition predicate, and a TrueGuardCondition predicate mayalso be specified. A FalseGuardCondition always evaluates to FALSEeffectively ensuring that the associated actions are never executed. ATrueGuardCondition always evaluates to TRUE ensuring that the associatedactions are always executed.

A first task performed by the UXM service 121 is to generate requests tosource applications following receipt of a request for a user. Operationof the UXM in performing this task is now described.

When a UserRequest message is received by the UXM service 121 (usuallyfrom the DT service 120), a UXM_MODIFIED parameter within the message ischecked. If this is set to FALSE, the message is directed to a sourceapplication without processing by the UXM. It this is set to TRUEprocessing is carried out as follows and a UserRequest event isgenerated.

The UserRequest event causes the UXM to locate within the IDM the entityspecified by the UXM_NODE_ID parameter. This entity then becomes auser's active aggregation point. In this case that node is the TreeNode178. Any predicates specified in a predicate data group associated withthat node are then checked. Assuming that all predicates are satisfied,the actions referenced by the entries of the integration data group (asdefined by their respective data groups) are then carried out. The UXMtraverses down through the UXM tree evaluating predicates and executingactions associated with each entity, each entity encountered typicallyproviding a list of actions, one or more of which may reference anappropriate source application. Details of actions which may appear inan integration data group are set out below.

Actions are in general associated with a single event type. However, itis possible to override this associated by using an EVENTMASK parameteris an action's data group. This parameter is an N-bit binary value andis set such that each bit represents a different event, and that theaction is associated with all events for which the respective bit is setto ‘1’—four example if four actions are used to trigger actions, theEVENTMASK parameter should be a four-bit binary value.

Actions typically associated with a UserRequest event are now described.

A UserRequestAction is by default associated with a UserRequest event,but may be associated with other events by using the EVENTMASK parameterin the manner described above. This action generates a new sourceapplication request which is targeted to the APPLICATION_CLASS of thesource application. A request will be a made to each source applicationwhich is required to produce the composite page.

The entries in an UserRequestAction data group specify informationrelevant to creating a request(s) for sending to particular sourceapplication(s), however it should be noted that details relating toconnection to that application are not included, as these are specifiedby the CL service 123 of AA node 107. Each source application requestwill include only information specified by the relevant action datagroup, and will not necessarily include parameters present in theIncomingUserRequest message.

A source application request will include an APPLICATION_CLASS parameterwhich specifies an application class name for the source application,and an APPLICATION_PATH parameter, which specifies a path for locatingthe application. Additionally, a source application request may includea request method indicating how data should be requested. This parametermay take a value such as HTTP_GET in the case of a HTTP request. Themessage additionally includes a string comprising zero or moreparameters which are picked up from the current context. If thisparameter is the empty string, then no values are added to the sourcerequest.

A DeflectUXMRequest action is again associated with a UserRequest eventby default, although this association can be overridden using anEVENTMASK parameter as described above. A DeflectUXM action generates asource application request of the type described above, but here theparameters for that request are obtained from the IncomingUserRequestmessage, not from the current context. This action is usually triggeredto re-use an original user request message, and the UXM merelydecomposes the message into parts relating to different pages of thesource application.

A UXMRequestLink action is associated with a UserRequest event, andcannot be overridden by using the EVENTMASK parameter in the mannerdescribed above. This action triggers a UserRequest event on an entitywithin the UXM tree identified by a TARGETNODE parameter. The receivingentity will then respond to the UserRequest event as specified by itsUXM entries. This action effectively adds an aggregation point to theUXM Tree.

A JumpToTreeNode action is again associated with a UserRequest event,but can be overridden using the EVENTMASK parameter. This action jumpsto a different branch of the UXM tree structure, and causes aUserRequest event on an appropriate entity. This differs from theUXMRequestLink action described above in that the current aggregationpoint is removed, and replaced with the specified target aggregationpoint.

A number of actions are concerned with manipulating values (typicallyname, value pairs (NVPs)) within the current UXM context. ACopyNVPAction action is associated with a UserRequest event, but can beoverridden using the EVENTMASK parameter as described above. ACopyNVPAction action copies sets an NVP at a specified target node to avalue obtained from a specified source entity. The action includesidentifiers of both the source and target entities, and details of thesource NVP and target NVP within those entities. If a target NVP is notspecified, as a default, it is assumed that the target NVP is the sameas the source NVP. Optionally, a prefix and/or suffix may be specifiedwhich is prepended or appended to the source NVP when it is copied tothe target NVP.

A ConcatenateNVPAction action is again associated with a UserRequestevent but can be overridden by the EVENTMASK parameter. This actionconcatenates a plurality of NVPs at a source entity and copies these toa specified NVP at a target entity. The action takes as parameters asource entity identifier (which defaults to the current entity if notspecified), a target entity identifier, a comma separated list of namesfrom NVPs which are to be concatenated, and the name of an NVP to becreated at the target entity. The value assigned to the created NVP willbe the concatenation of the values from the NVPs in the comma separatedname list.

An AddSequenceListener action is associated with a UserRequest event butcan be overridden using the EVENTMASK parameter if necessary. Thisaction sets the context of the current entity as a sequence listener ofan entity specified by a TARGETNODEID parameter.

A StoreRemoteServiceCredential action is associated with a UserRequestevent but can be overridden using the EVENTMASK parameter if necessary.This action allows information about a remote service (e.g. a sourceapplication) to be stored as a parameter in the context of the currententity. The information is stored as a NVP, and is typically securityinformation related to a source application. The action includes aREMOTE SERVICE parameter which is an identifier for a remote service(e.g. a source application), and a CRED_TYPE parameter which is used toindicate the type of credential being stored. The CRED_TYPE parametercan be set to USRPWD or IDONLY. If CRED_TYPE is set to USRPWD, the NVPstores both a username and a password. If it is set to IDONLY, only ausername is stored. The name of the NVP is of the form“credential.<remote_service>.username|password”, where <remote_service>is an identifier obtained from the REMOTE SERVICE parameter.

Having generated one or more source application requests in response toUserRequestAction actions and/or DeflectUXMRequest actions (in additionto carrying out any other actions which may be necessary), the createdsource application requests are used to create OutgoingUserRequestmessages which are then usually targeted to a DT service 124 of an AAnode.

A second function of the UXM is to compose responses received fromsource applications to form the composite application. The UXM serviceof the CA node generally receives source application responses from theDT service 124 of the AA node 107. An outline of the actions carried outby the DT service 124 of the AA node 107 is now presented, to aidunderstanding of the operation of the UXM.

The DT service 124 of the AA node 107 recognises pages returned bysource applications using predefined rules. The recognition process isdescribed in further detail below, but it should be noted that the DTattempts to recognise normal pages first, then error pages. Assumingthat the page is recognised a UXM object tree representing that page isgenerated.

Referring to FIG. 31, there is illustrated a simple example conversionwhich may be carried out by the DT service 124 to generate anappropriate UXM object tree. A HTML document 222 comprises a table 223,which in turn comprises a form 224 and an image 225. The DT servicegenerates a UXM object tree 226 from this HTML document. The UXM objecttree 226 comprises four UXM objects, one for each element of the HTMLdocument 222. It can be seen that these UXM objects are hierarchicallyarranged such that a . . . Body object 227 is at the root of the tree, a. . . Body.Table1 object 228 is a child of the . . . Body object, and a. . . Body.Table1.Form object1 229 and a . . . Body.Table1.Image1 object230 are children of the . . . Body.Table1 object 228. Thus, thehierarchy of the UXM object tree 226 mirrors that the of the HTMLdocument 222. It should be noted that each entry in the UXM object tree226 is prefixed by “ . . . ” to indicate that in practical embodimentsof the invention, the names of entries are prefixed by an appropriatesource application name. Operation of the DT service 124 is described infurther detail below.

Having created the plurality of UXM objects, these are sent to the UXMservice 121 of the CA node 106.

A message is received by the UXM from the CA service of the AA node 107.If the message comprises one or more UXM objects, a UserResponse eventis generated by the UXM. UXM objects may be nested within a receivedmessage, and in such a case the UXM unnests the received UXM objects tocreate individual UXM objects as appropriate. The created individual UXMobjects are then copied to the user's context at the appropriate entityof the UXM tree structure and form the UXMObject tree. The appropriateentity can be identified using the ID parameter of the receivedUXMObject which, as described above, will correspond to the ID of anentity within the UXM tree.

The UserResponse event causes the UXM to traverse the UXM tree beginningat the entity specified by the ID parameter of the received UXMObject.For each entity within the tree which is processed in this way, the UXMdetermines if all predicates (specified in appropriate predicate datagroups) are satisfied for each entity. If the predicates are satisfiedfor a given entity, the actions associated with that entity (asspecified in an actions data group) are executed. Details of actionswhich are generally associated with UserResponse events are nowdescribed.

A RegexTransformNVPValue action is by default associated with aUserResponse event, although this association can be overridden usingthe EVENTMASK parameter as described above. This action sets a NVPwithin the user's context, for a target entity within the UXM tree. Theaction specifies a SOURCENODEID parameter which defaults to the currententity if not specified, an a mandatory SOURCENAME parameter whichspecifies an NVP within the source entity. The action may optionallyspecify TARGETNODEID parameter identifying a target entity and aTARGETNAME parameter identifying a NVP within the target entity. Ifthese are not specified, the TARGETNODEID is set to be equal to theSOURCENODEID and/or the TARGETNAME is set to the equal to theSOURCENAME. The action also includes a REGEX parameter which specifies aregular expression which is applied to the source NVP to generate thetarget NVP.

Regular expressions will be well known to those skilled in the art as away of manipulating strings within computer programs. In the case ofsome embodiments of the present invention regular expressions of thetype used in the Perl5 programming language are preferably used,although it will be readily apparent to those skilled in the art thatregular expressions of different formats can also be used in embodimentsof the present invention.

A CopyUXMObjetValueToTargetContext is again associated with aUserResponse event, but can again be overridden using the EVENTMASKparameter as described above. This actions sets an NVP in a user'scontext at target entity within the UXM tree. The value to which the NVPis set is taken from a UXM object at a source entity. The action takesSOURCENODEID and TARGETNODEID parameters which respectively specifysource and target entities within the UXM tree. If these parameters arenot set, by default the current entity is used. The action has amandatory TARGETNAME parameters which specifies an NVP within the targetnode which is to be set.

A SetUXMObjectProperties action is again associated with a UserResponseevent, but can be overridden as described above. The action specifies aplurality of NVPs which are set within the UXM object at the currententity of the UXM tree.

A SetTargetUXMNode action is associated with a UserResponse event, butcan be overridden using the EVENTMASK parameter. This action setsattributes of a UXMObject at an entity specified by an ACTIONTARGETparameter, which defaults to the current entity if no value isspecified. The UXM object specified by the ACTIONTARGET parameter isupdated so that it points to a UXMTreeNode relating to a differententity within the UXM object tree specified by a mandatory TARGETNODEparameter.

A CopyUXMObjectToTargetContext action is again associated with aUserResponse event but can be overridden. This actions sets theUXMObject at an entity specified by a SOURCENODEID parameter to point tothe UXMObjects specified by an entity given in a TARGETNODEID parameter.The SOURCENODEID parameter is optional, and defaults to the currententity if not specified.

A RelocateUXMObject action is associated with a UserResponse event andcannot be overridden using the EVENTMASK parameter. This action sets themode parameter within a UXM object associated with an entity specifiedby a TARGENODEID to “Relocate”, and results in the object beingrelocated (i.e. moved rather than copied) to a new parent.

A DeleteUXMObjectFromTargetContext action is again associated with aUserResponse event but can be overridden. This action deletes the UXMobject associated with the entity specified by a mandatory TARGETNODEIDparameter.

A ConditionalCopyOfUXMChildObjectToTargetContext action is associatedwith a UserResponse event but can be overridden. This action compares avalue of an NVP specified by a SOURCENVPNAME within the context of thecurrent entity with the same NVP in an entity referenced by aCHILDNODETOCOMPARE parameter. If the comparison is such that apredetermined condition is satisfied, a UXM object identified by aCHILDNODETOCOPY parameter is copied to the context of an entityidentified by a TARGETNODEID parameter. It should be noted that theparameters CHILDNODETOCOMPARE and CHILDNODETOCOPY are specified relativeto the current entity, and not as absolute path names.

A CopyUXMObjectValue action is again associated with a UserResponseevent and cannot be overridden using the EVENTMASK parameter. Thisaction copies values from a UXM object present at an entity identifiedby a SOURCENODEID parameter to a UXM object present at an entityidentified by a TARGETNODEID parameter.

A CopyUXMObjectValueFromTargetContext is again associated with aUserResponse event but can be overridden. This action will copy a valueof an NVP identified by a SOURCENVPNAME parameter in the context of anentity identified by a SOURCENODEID to a UXM object at an entityidentified by a TARGETNODEID parameter.

A RegexTransformUXMObjectValue is by default associated with aUserResponse event but this can be overridden using the EVENTMASKparameter. This action retrieves a UXM object from an entity identifiedby a SOURCENODEID parameter, applies a regular expression specified by aREGEX parameter and writes the resulting value to an entity identifiedby a TARGETNODEID parameter.

A UXMObjectNotification action is associated with a UserResponse eventand cannot be overridden. It takes no parameters. It copies a UXMObjectfrom a current context to the child of an active aggregation pointhaving the same name. For example, if the action is associated with anentity having a path S1.A1.A2 and the active context is S1.C1, the id ofthe current entity (i.e. A2) is used to locate an entity within theactive context which should refer to the UXM object. In this case, thatis S1.C1.A2.

Those actions which relate to manipulation of Externals and which are bydefault associated within a UserResponse action are now described.

A LoadExternalID action can have its association overridden using theEVENTMASK parameter described above. This action retrieves an ExternalIDwhich is specified by an EXTERNALENTITYCLASS parameter and anAPPLICATION_CLASS parameter from the current context, and writes thisvalue to a UXM object associated with the current context.

A StoreExternalID action can again have its association overridden byuse of the EVENTMASK parameter. This action saves the value of the UXMobject associated with the current entity as an ExternalId having anapplication class identified by an EXTERNALENTITYCLASS parameter.

A ClearExternalIDs actions can be overridden, and clears all externalID's from the context of an entity identified by a SOURCENODEIDparameter.

Having traversed the tree, and executed all actions for which predicatesare satisfied, execution returns to the user's active aggregation point(i.e. the entity within the UXM tree which received a UserRequest eventto trigger the source application requests which in turn generated theresponse from the AA). Each node of the UXM tree beneath the node whichreceived the UserRequest event is interrogated to ascertain whether ornot it has received its UXM object. When all entities beneath the entitywhich received the request have received their objects, a UXMAggregateevent is created to cause aggregation.

It should be noted that in preferred embodiments of the presentinvention, each node in the UXM tree can specify that a UXM object ismandatory or optional within its control data group using a BooleanisMandatory variable, which defaults to FALSE where not specified. Insuch embodiments, a UXMAggregate event is created as soon as allmandatory UXMObjects are present. However, in alternative embodiments ofthe invention it may be desired to await all mandatory UXM objects, thenapply a predetermined time out, after which aggregation is carried outusing those objects which have been received.

A UXMAggregate event causes the UXM to traverse all entities which arechildren of the current entity, and execute all actions specified in theintegration data group which are triggered by a UXMAggregate event. Someactions which are associated with UXMAggregate events are now described.

An AddUXMObjectAction action is by default associated with aUXMAggregate event, but this can be overridden using the EVENTMASKparameter described above. This action creates a new UXMObject and addsthis to an entity identified by a TARGETNODEID parameter. This actiontherefore allows UXMObjects to be created at any point in the UXM tree.An OBJECTID parameter specifies a name for the new UXMObject, andOBJECTTYPE and MODE parameters specify the created object's type andmode as described above. A RELATIVETO parameter allows the TARGETNODEIDto be specified relative to a an entity specified by the RELATIVETOparameter, although if RELATIVETO is not specified, it defaults to thetop level.

As described above, the AddUXMObjectAction action creates a new UXMobject at a target entity. An INSIDETARGET parameter allowsconfiguration of what should happen if a UXM object already exists atthe target entity. If the parameter is not specified, and the UXM objectalready at the target entity is of type “container” the current objectis provided as a child of the existing UXM object at the target entity.If the INSIDETARGET parameter is set to TRUE, the new UXMObject is setas a child of the existing UXM object. If the INSIDETARGET parameter isset to FALSE, the existing UXM object becomes a child of the new UXMobject at the target entity.

A CreateUXMObject action is by default associated with a UXMAggregateevent, but this can be overridden using the EVENTMASK parameter asdescribed above. This action creates a new UXMObject and adds it to theuser's context at the targeted entity. It should be noted thateverything which can be achieved using a CreateUXMObject action can becreated by an AddUXMObjectAction which has appropriate parameters. Thatis the CreateUXMObject action can be thought of as an AddUXMObjectActionwith some hard-coded parameter values.

An AggregateChildObjects action is by default associated with aUXMAggregate event. This cannot be overridden using the EVENTMASKparameter described above. This action is essential to creatingcomposite user interfaces. It aggregates all UXMObjects at contexts ofentities which are children of a target entity, and creates a newUXMObject at the targeted context. Any UXMObjects which have a mode setto delete are ignored for the purposes of this action, all others areinserted as nexted UXMObjects. A parameter for the action specifies thetarget entity.

An AggregateNamedContexts action is by default associated with aUXMAggregate event, but this can be overridden using the EVENTMASKparameter described above. This action allows zero or more entities tobe specified, and the UXMObjects associated with each of those entitiesare aggregated to form a new UXMObject at an entity specified by aTARGETNODEID parameter.

A DeleteUXMObjectAction action is by default associated with aUXMAggregate event, but this can be overridden using the EVENTMASKparameter described above. This action will set any UXMObjects presentat an entity defined by a TARGETNODEID parameter to have a Mode ofDelete, meaning that it will not be included in aggregation actions (seeabove). It should be noted that this action does not delete objects, butsimply sets their mode parameter to have a value delete.

An AddHTMLElementAction action is by default associated with aUXMAggregate event, but this can be overridden using the EVENTMASKparameter described above. This action is used to inset a HTML elementinto a UXMObject in the context of an entity identified by aTARGETNODEID parameter. In order for this action to work, the UXMObjectmust have a type parameter as specified by anENLTMERATED_HTML_ELEMENT_TYPE parameter within the AddHTMLElementActionaction. Possible values for the ENUMERATED_HTML_ELEMENT_TYPE parameterare html_radiobuttongroup, html_checkboxgroup and html_dropdownlist. AnAddHTMLElementAction also takes parameters which specify a name, a valueand text for the HTML element. For each type of HTML element furtherparameters relevant to that element may be specified by theAddHTMLElementAction.

If a UXMObject at a target context has a type of html_radiobuttongroup,an AddHTMLRadioButton action is by default associated with aUXMAggregate event, but this can be overridden using the EVENTMASKparameter described above. This action adds a radio button to the radiobutton group represented by the UXMObject.

Having executed all actions appropriate to a UXMAggregate event, theentity within the UXM tree which received the user's request has aUXMObject which represents the requested composite page, which can bepassed to the DT service 120 of the CA node 106.

It should be noted that UXMObjects are passed between services bycreating an XML representation which is then used as a payload of amessage to be transferred between services. This is achieved using atoXML method provided by a UXMObject.

It should be noted that the UXM comprises further functionality inaddition to that which is described above. Actions triggered by variousevents have been described above. It should be noted that some actionsmay by default be associated with no particular event, and in such casesthe EVENTMASK parameter must be used to determine association.

The UXM service 121 allows JavaScript scripts to be associated withgiven entities within the tree, and these scripts can be executed byinclusion in an action data group, in the manner described above. TheJavaScript is interpreted by the UXM at run time, and executed toperform the necessary functions. It will be appreciated that scripts mayneed to communicate with the UXM to obtain relevant data. This isachieved by providing a UXMRUNTIME object which can be accessed byscripts.

Methods exposed by a Java object can be invoked directly from a script,assuming only that the script has the Java object's identifier. Themethods exposed by a UXMRUNTIME object allow scripts to be effectivelycreated.

A UXMRUNTIME object allows various operations to be carried out on UXMobjects specified by a path within the UXM tree. This path is a stringcomprising the name of an entity prepended by a ‘.’ prepended by thename of its parent entity, which in turn is prepended by a ‘.’ and itsparent entity name. For example the string “MyTRN.page1.FormElement”denotes an entity “FormElement” which has as its parent an entity“page1” which is a child of a TreeRootNode entity “MyTRN”. It should benoted that fully specified paths must always be used within UXM scripts.This is because a UXM script is not considered to be executed from aparticular entity within the UXM tree, and accordingly a relative pathwill have no well defined meaning.

Methods provided by the UXMRUNTIME object are now described.

A prepareUXMObject method takes a path of the form described above as aparameter and allows the UXMObject specified by the path to be accessedby the script. The thread in which the script is executing is blockeduntil the UXMObject is returned, and the UXMObject's availability cantherefore be assumed. This method will effectively trigger a UserRequestevent on the node specified by the path parameter, and it is thereforeimportant to ensure that nodes which are to be used in this way byscripts are provided with actions triggered by UserRequest events. Anentity targeted by this method is typically a source page, and thismethod effectively creates a request to fetch the source page, which issubsequently provided to the script. If the UXMObject cannot be providedto the script for any reason, an error field within the UXMRUNTIMEobject will contain details of any exception which was thrown. The errorfield of the UXMRUNTIME object should therefore be checked (see below)before attempting to the use the requested UXMObject. AprepareUXMObjects method functions analogously to prepareUXMObject, buttakes an array of paths as its parameter, and returns all requestedUXMObjects.

A getUXMObject method retrieves a UXMObject from an entity specified bya path parameter. A setUXMObject method sets a UXM object at a specifiedentity to a UXMObject provided by a parameter of the method.

The UXMRUNTIME object provides various methods for accessing andmanipulating NVPs at a given entity within the UXM tree. A setNVP methodallows a specified NVP to be set to a specified value at a specifiedentity within the UXM tree. A getNVP method allows the value of aspecified NVP to be obtained from a specified entity. A clearNVPs methodallows all NVPs to be cleared from a specified entity. AgetRequestParameter returns the value of a request parameter at aspecified entity in the UXM tree.

It was mentioned above that the UXMRUNTIME object includes a field inwhich details of any errors are stored. A hasException method returns avalue indicating whether or not an exception occurred during processing,and a getException method returns details of any exception thatoccurred.

Error details may also be stored within a user's context at an entity ofthe UXM tree. Various methods are provided to access such error detailsA getErrorDetail method gets details of such an error message from anentity specified by a path parameter. A requestHadError method returns avalue indicating whether or not an error occurred. A getErrorLodationreturns the name of a service (e.g. UXM, DT, CL) at which the erroroccurred.

A getErrorMessage method returns details of the error message generated,and getMajorErrorCode and getMinorErrorID methods return details oferror codes. All these methods take a path specifying an entity withinthe UXM tree as a parameter.

In general terms, scripts can be used to replace the mechanismsdescribed above for carrying out aggregation. When a script is used anintegration data group will typically contain a single entry referencingan action data group for the script within an action library whichcontains a script name and details of the script.

If a script is used for aggregation, it will be appreciated that it isimportant to ensure that a mechanism is provided such that the scriptknows when all necessary source pages have been received by the UXM asUXMObjects. This is provided by a ScriptResponseNotification action,which is provided in an action library, and included in the integrationdata group of each source page, and which is triggered after processingof a UserRequest event.

The runtime memory space of the script will include details of allrequested source pages. When a UXMObject corresponding to a source pageis received by the UXM the UXMRUNTIME object is updated by theScriptResponseNotification. The UXMRUNTIME object in response to theScriptResponseNotification then updates the runtime memory space of thescript.

It should be noted that when scripts are used, two parameters which maybe specified in the control data group associated with an entity are ofsome importance. An EVENTORDER parameter controls the order in whichchild entities are processed. A HANDLEERROR parameter needs to be set toTRUE, so as to allow the script to process any errors that may occurduring execution, instead of the global error handling generallyprovided by the composer.

The scripting functions described above are provided by the BeanScripting Framework (BSF) which is provided by the Java programminglanguage. This framework allows a number of different scriptinglanguages to be used, although as described above, JavaScript is used inpreferred embodiments of the present invention. It should be noted thaton first execution the JavaScript script will be complied to generateJava Byte Code which can be interpreted by a Java Virtual Machine. Itwill therefore be appreciated that a script will take longer to executeon its first execution.

Operation of the DT service is now described. The DT service includes aplurality of transformation engines which may be applied to data tocause data transformations. The transformation engines are stateless,and a single instance of each engine exists within a particular DTservice. These transformation engines are now described in furtherdetail.

An APICallExtemalizer translates data from internal representations toexternal representations using ExternalIDs described above and such datacan then be used by the CL service to generate API calls. A DOMtoStringtransformation engine converts a DOM object representing an HTML file(typically received from a source application) into a string.

An IDExternaliser transformation engine and an IDInternalizertransformation engine respectively convert internal IDs to external IDsand external IDs to internal IDs.

The DT service includes some transformation engines to process andcorrect HTML provided to it. A HTML TagBalancer tag balances incomingHTML to produce well formed HTML as output. A HTMLTidy transformationengine makes use of Jtidy to correct malformed HTML, and ensures thatthe output is XHTML compliant.

A JavaSpecializedEngineExecutor transformation engine executesspecialized transformations that are hardcoded into a Java class. TheJava class specified for this engine must implement a predefinedJavaEngine interface specifying a single execute( ) method which is usedto transform data, so that it can be known that the Java class willinclude this method which is required for transformation.

A Marshaller transformation engine makes use of the Castor framework toconvert Java objects into XML, as described at http://castor.exolab.org.This engine can be used for generic transformations.

A PageResolver transformation engine recognizes response pages andapplies appropriate extraction configuration. It first tries torecognize normal pages, then error pages and finally applies a defaultextraction if no match is found.

A RegEx transformation engine takes a string input, applies a regularexpression to it and returns a string as output.

A RegexAggregator transformation engine is used to insert new userinterface elements into a user interface. The configuration of thisengine is a single regular expression string. Some regular expressionshave special meanings, and will be substituted before the regularexpression is applied:

-   -   _VALUE_ is replaced by the value of the OBJECT_ID parameter in        the engine definition data-group.    -   _NAME_ is replaced by the value of the NAME parameter in the        engine definition data-group.

A RegexExtractor transformation engine is used to extract user interfaceelements in UXM format using regular expressions. It also marks up theinput string where the string fragment was extracted.

A UIAggregator transformation engine is used to aggregate the UXM userinterface data into a form suitable to return to the user. It istypically only used in the CA.DT. A UIExtractor transformation engineconverts the incoming response page into UXM Objects which can beforwarded to the UXM service. This is used in the AA.DT.

An Unmarshaller transformation engine makes use of the Castor frameworkto convert XML into Java. A UxmObjectDecomposer transformation engine isused in the process of aggregating UXM user interface data. Itdecomposes complex UXM objects into simpler ones so that the aggregationcan take place in later stages. A UxmObjectToString extracts the datafrom a UXMObject and returns it as a string.

An XMLParser transformation engine takes a string as input and parses itinto a DOM tree. The resulting XML tree is the output of the engine. AnXpathExtractor transformation engine is used to extract user interfaceelements in UXM format using XPath. It also marks up the input stringwhere the string fragment was extracted. It is used primarily in theUXM. An XSLTransformer transformation engine takes an XML document asinput, applies a XSL style sheet to it and returns an XML document asoutput.

The transformation engines outlined above provide a variety of basicfunctions which are required by a DT service. The transformation enginesare used by transformation actors which act on the data to transform it.There are essentially two types of transformation actors: atomic actorsmake use of transformation engines directly, while group actors useother transformation actors.

An atomic actor holds configuration data indicating how a transformationengine should be used to carry out the necessary transformation. Forexample, an atomic actor using an XSL transformation engine may beconfigured using an XSL style sheet. The output will then be a DOMobject (see above). When called, the actor will pass the input data andthe configuration data to the transformation engine to cause thetransformation to be effected.

An atomic actor has a type parameter which is set to “base” whichindicates that the transformation actor is an atomic actor. It has atextual description of the transformations which it carries out. It hasa EngineID parameter which identifiers one of the transformation enginesset out above which is to be used by the actor. A configurationparameter is represented by a string. This will typically be a regularexpression or alternatively a file name of an XSL style sheet. Someactors will have multiple outputs, while other actors will always have asingle output value. This is represented by a MultipleOutputs parameterwhich is set to TRUE if multiple outputs are allowed, or FALSE ifMultipleOutputs are not allowed. If an actor for which MultipleOutputsis set to FALSE produces multiple output data at run time, the data ismerged using a Java class specified by a DataMerger parameter. A Timeoutparameter provides a timeout, preferably in milliseconds.

A group actor combines one or more other transformation actors. Thetransformation actors being grouped may be atomic actors or groupactors, and can be executed either in parallel or sequentially, or asalternatives.

A group actor has a type parameter which is set to “group”, adescription parameter specifying a textual description, and a parameterTransformationIDs which is a list of actors contained within the groupactor. A GroupType parameter can take values of “sequence”, “parallel”and “switch”. If the GroupType parameter is set to “sequence” all thecontained transformation actors are executed sequentially, in the orderin which they are listed in a Transformation IDs parameter. If theGroupType parameter is set to “parallel”, all the containedtransformation actors are executed in parallel. If the GroupTypeparameter is set to switch, a single actor will be chosen at run time toact upon the passed input data. A LateInitialization parameter takes aBoolean value indicating whether or not late initialisation should beused. That is, this parameter indicates whether the transformationengine should be initialised at start up (if LateInitialization is setto FALSE), or when the transformation engine is used for the first time(if LateInitialization is set to TRUE). A group actor also hasMultipleOutputs, DataMerger and Timeout parameters, as described abovewith reference to atomic actors.

In preferred embodiments of the present invention some atomic actors andsome group actors are provided by default. Details of thesetransformation actors are now described.

Atomic actors provided by default are as follows. A NOP actor performsno operation, which can be necessary in the DT in cases where notransformation is required. Three further atomic actors simply maketransformation engines described above available as actors. AHTMLTagBalancer actor makes the HTMLTagBalancer transformation engineavailable as an actor, a UXMObjectDecomposer actor is used by the DTservice of the CA and makes the UXMObjectDecomposer transformationengine available as an actor. A UXMObjectToString actor makes theUXMObjectToString transformation engine available as an actor, and anXMLParser actor makes the XMLParser transformation engine available asan actor.

A PageResolver actor is used by the DT service of the AA to recognisepages returned by source applications. It picks up details of the pagesto be recoginsed from the appropriate parts of the IDM, as describedabove. A UIExtractor actor is used by the DT service of the AA toconvert pages into UXMObjects, again appropriate configurationinformation is provided by the IDM.

A UIAggregator actor is used by the DT service of the CA to convert UXMobjects into a form suitable for returning to a user as part of acomposite application. A URLRewrite actor is used to update anynecessary URLs, forms and/or frames in a page which is to be returned toa user.

A plurality of group actors are also provided by default. Asequence.IncomingUserResponse actor is a sequence of transformationactors which can be applied to a typical incoming user response message,to convert the page response into UXM form. It applies the PageResolveractor and the UIExtractor actor described above.

A sequence.OutgoingUserResponse actor is sequence of transformationactors to apply to a typical outgoing user response message to convertthe UXM Object tree into the resulting page to return to the user. Itapplies an actor to convert a marshalled UXMObject tree into a XML treeand then aggregates the various components according to information inthe XML tree. The result is converted to a string representing the pagewhich is returned to the user.

A sequence.UIAggregation actor comprises a sequence of transformationactors to apply to aggregate the components of a page into the finalpage. It applies other transformation actors to decomposes and aggregateand then uses the atomic actor UIAggregator described above.

A sequence.UIAggregation.DecomposeAndAggregate is a sequence oftransformation actors which are applied to get the page elements readyfor aggregation. It first decomposes the top most UXMObject using theUXMObjectDecomposer actor. It then recursively goes down through thetree repeating the same action.

A switchgroup.UIAggregationRecursion is a switch group of transformationactors. It goes down through the UXMObject hierarchy, choosing at eachstage whether the UXMObject contains other UXMObjects or not.

A sequence.UIExtraction actor comprises a sequence of transformationactors which are applied to extract the components of a page into aUXMObject tree. It decomposes and aggregates, then uses the atomic actorUIAggregator

A switchgroup.UIExtractionRecursion actor is a switch group oftransformation actors. It goes down through the UXMObject hierarchy,choosing at each stage whether the UXMObject contains other UXMObjectsor not.

Operation of the DT service within the AA node for a particular sourceapplication is illustrated in FIG. 32. Data is received from a sourceapplication is denoted by an arrow 231. This data is first passed to atransformation engine 232 which makes any necessary amendments to URLreferences included in the received source data. This can be achievedusing, for example, the RegEx transformation engine described above. Asecond transformation engine 233 performs any generic URL amendmentsthat may be necessary, and can again be the RegEx transformation enginedescribed above. A HTML tag balancer transformation engine 234 (of thetype described above) is then used to ensure that the produced HTML iswell formed.

The output of the HTML tag balancer is input to a group actor 235 whichis configured to recognise and process the received source page. Thegroup actor 235 comprises a suitable PageResolver transformation engine236 which is configured to recognise predefined pages, and a group actor237 which comprises one or more of the transformation engines describedabove, which together act to extract user interface elements fromrecognised pages.

Having described configuration of the composer, and the key servicescontained within its nodes, its operation in providing compositeapplications, as outlined above with reference to FIG. 15, is nowdescribed in further detail, referring again to FIGS. 14 and 15.

Processing typically begins when a user using the web browser 126 makesa HTTP request which is subsequently directed to the web server 12. Theservlet 117 operating on the web server 12 determines whether or not theURL entered relates to a page provided by the composer. If it isdetermined that the URL does not involve the composer, the web serverobtains and displays the requested web page in a conventional manner. Ifthe URL is to be provided by the composer, the servlet 117 interceptsand processes the HTTP request. This involves converting the HTTPrequest into an IncomingUserRequest JMS message.

It will be appreciated that some requests will require authentication.Authentication is handled using cookies. When a user first attempts toaccess a page requiring authentication the request will be interceptedby the CL service of the CA node, and this service will determinewhether or not the request includes any required cookie. If no suchcookie is present in the request, the user will be presented with a pageinto which suitable authentication data (e.g. username and password) isentered. This data is sent to the web server, and onwards to the ALFservice 126 of the ALF node 108, where the input authentication data ischecked against data stored in the ALF database. Assuming that thisauthentication process is successful, the user's original request isprocessed. A cookie is stored on the user's computer, and in the case ofsubsequent requests, this cookie is read by the web server, forwarded tothe CL service of the CA node, and then forwarded to the ALF service 126to enable authentication using the ALF database 110. The followingdescription assumes that all necessary authentication has beensuccessfully carried out.

Creation of the JMS message is carried out as specified by theappropriate configuration data within the IDM. Having created anappropriate IncomingUserRequest message, and determined to where itshould be sent using the target parameter within the weblistener datagroup 210 (FIG. 28) it is then necessary to locate an appropriateinstance of the target service which can accept the created message.

The listener performs load balancing over JMS, so that a plurality ofinstances of a target service can be used concurrently, and requests canbe effectively distributed between the plurality of composers. The JMSproperties file for the listener (described above) includes aresolverprotocol.roundrobin.target parameter which specifies a loadbalancing algorithm which is to be used such as, for example the roundrobin algorithm. This parameter will also specify how many instances ofthe target (in this case the CL service of a CA) to expect.

When an instance of the target service starts up, it declares itselfusing an appropriate JMS message, and the listener will then know thatmessages can be sent to that instance of the target service. When alistener needs to send a message to an instance of the target service(e.g. to the CL service of a CA) a broadcast message is sent to allinstances of the service registered with the listener. The listener willthen await a response from all registered targets, any responses fromnon-registered targets are simply ignored. When all expected responseshave been received, the listener chooses one instance of the targetservice in accordance with the specified algorithm, and theIncomingRequestMessage is sent to the selected instance.

Having selected a target to receive messages from a particular user, thelistener ensures that subsequent messages from that user are directed tothe same composer. This need not necessarily be the case, and isdetermined by an add affinity parameter within the IDM. Similarly, theIDM configuration for the composer has an add listener affinityparameter which ensures that messages for a particular user are alwaysdirected to the same listener.

The transmitted IncomingUserRequest JMS message will be received by theCL service 199 of the CA node 106 via its ML service 118 which isresponsible for JMS messaging. On receipt of the IncomingUserRequestmessage, the CL may perform authentication using log on parametersspecified in the IncomingUserRequest message, by using the ALF serviceof the ALF node in the manner described above. Assuming thatauthentication is successful, the message is simply passed to the DTservice 120 of the CA node. The passage of messages between services, isdetermined by data stored within the message objects, as describedabove.

The DT service 120 retrieves configuration data pertinent to the actionsrequired in response to receipt of an IncomingUserRequest message. Thedata is retrieved by accessing the IDM data structure (FIG. 22), andlocating the DT.Applications data group 153. The data group 154pertinent to the composite application specified in theIncomingUserRequest message is then located, and the action referred 158referenced by the InocmingUserRequest message in the data group 154 isthen identified and carried out. On receiving an IncomingUserRequestmessage, no transformation is usually required, and the DT service 120therefore performs no operation, as specified by the data group 158. Themessage is then passed to the UXM service 121 of the CA node 106.

The IncomingUserRequest message is typically generated from a HTTPrequest as described above. A suitable HTML fragment for such a requestis shown in FIG. 33. It can be seen that the third line specifies thatthe composite application's application class name is “CompApp1”. Thefourth line specifies that the request requires modification by the UXM,the fifth line specifies a node in the IDM tree structure relevant tothe application, and the sixth line specifies a node in the IDM relevantto the page which generated the request. All this data is encapsulatedwithin the IncomingUserRequest message.

The UXM will locate a “CompApp1” node within the UXM tree, and traversedown the tree structure, executing any actions for which the predicatesare satisfied. These actions will typically involve creating one or moreOutgoingUserRequest messages directed to appropriate sourceapplications, which are forwarded to the source applications via the AAnode 122, and these messages are therefore forwarded to the AA node.

In the present example, an AA node is present within the same process asthe CA, and can therefore be located without problems. However, if nosuch node exists within the current process. The message(s) areforwarded to the ML service 118 of the CA node 106 and the ML servicethen attempts to locate an appropriate AA node within a differentprocess using JMS, as described above with reference to FIG. 12D. When asuitable node has been located, the message(s) are forwarded to the MLservice of that node, and onwards to the CL service of that node. UsingJMS in this way allows convenient inter-process communication,regardless of the distribution of processes between physical machines.

An OutgoingUserRequest message is received by the DT service 124 of theAA node 107. The DT service must transform the OutgoingUserRequest intoa form understandable by the target source application. In many cases,there will be no action required by the DT at this stage as shown in theexample configuration of FIG. 23, where it can be seen that theOutgoingUserRequest entry of the DT.App.firstbyte data group 161references a no operation action 162. The OutgoingUserRequest message istherefore forwarded to the CL service 123 of the AA node 107.

The CL service 123 uses configuration data stored within the IDM tolocate a data group representing the correct source application (e.g.the g2config data groups 145, 147 of FIG. 21). This data group willspecify any authentication information which must be included in arequest to that source application. In order to obtain suchauthentication information the CL service 123 requests authenticationdata from the ALF service 126 of the ALFNODE 108, and this data is thenfetched from the ALF database as indicated by data in the IDM.

As described above, the IDM configuration for a CL service alsospecifies parameters which are used to connect to the appropriate sourceapplication (specified in a connection data group). The CL service willuse these parameters to determine the format of request which should begenerated for onward transmission to the source application. Forexample, this may be a HTTP request directed to a particular port of aparticular host. This request is then transmitted to the sourceapplication.

The source application will process received request messages in aconventional manner, and data output in response to the request is inturn received by the CL service 123 of the AA node 107.

The CL service 123 receives the data from the source application, andforwards this data to the DT service 124 of the AA node 107. At thisstage the DT service 124 must act upon the received data to transform itinto a form suitable for sending to the UXM service 121 of the CA node106. This processing will be of the type illustrated in FIG. 32 above.

The created UXMObjects are then forwarded to the UXM service 121 of theCA node 106. The UXM will record the received objects within the UXMTree as described above, and when all necessary data has been received,aggregation will occur to create one or more UXMObjects representing therequested composite page. The created UXMObjects are then forwarded tothe DT service 120 of the CA node 106, in one or more messagescontaining XML versions of the created UXMObjects.

The DT service 120 of the CA node 106 must then receive the messages,recreate the UXMObjects, and use data from the IDM configuration todetermine how to convert the received UXMObjects into a form suitablefor output to the user. Suitable forms may include HTML, or plain text.

It should be noted that by using an internal form until the compositepage is processed by the DT service 120 of the CA node 106, the systemdescribed above can easily by adapted to handle different output types,simply by adding appropriate configuration data to the IDM for the DTservice 120. This allows an effective decoupling of the composer fromthe output format required. Similar decoupling can be provided whenhandling input data.

The created output data is then forwarded by the DT service 120 to theCL service 119. The CL service uses the IDM data structure to determinethe protocol which should be used to return the composite page to theuser, usually via the servlet 117 of the web server 12.

Referring back to FIG. 14, operation of the administration terminal 112which is connected to the service 13 by means of the connection 113 isnow described. It is preferred that the administration terminal 112 isconnected to the server by a network connection, and a conventionalTransmission Control Protocol/Internet Protocol (TCP/IP) connection ofthe type used in Internet networks can suitably be used. Theadministration terminal may operate by running a web browser andaccessing an adminconsole HTML document which is provided on a suitableport number of the server (e.g. port 8080).

When a user has logged onto the administration server, it is possible tocreate users, and roles. Users are allocated to roles, and the roles towhich a user is allocate determine the actions which may be performed bythat user. Roles specify commands which may be executed by their usersand may also specify child nodes which inherit their properties.

When roles have been created users can be allocated to created roles.Users can be removed from roles as necessary, and deleted if no longerrequired. If a role is deleted, data for all users allocated to thatrole is automatically updated. The administration terminal can also beused to set up a user's service credentials, that is the security dataneeded by a user to access various source applications used within thecomposite applications.

Although the embodiment of the invention described herein is implementedusing the Java programming language it will be appreciated that theinvention is in no way restricted to a Java implementation. Indeed, theinvention can be implemented using any appropriate high level computerprogramming language. However, it is preferable to use an objectoriented programming language to obtain the benefits of reuse andencapsulation which are inherent in such computer programmingtechniques.

Although the present invention has been described hereinbefore withreference to particular embodiments, it will be apparent to a skilledperson in the art that modifications lie within the spirit and scope ofthe present invention.

1. A method of directing messages within a computer system, wherein: amessage is to be directed to a predetermined set of services; eachservice executes a command specified by the message; the messagecomprises details of the predetermined set of services; and each servicein the predetermined set of services uses said details to determinewhether the message should be sent to another service, and if it isdetermined that the message should be sent to another service transmitsthe message to an appropriate service. 2-146. (canceled)